Add kernel-offset file and make rcu_read_[un]lock() included

__rcu_read_[un]lock() are so simple functions and called so frequent, it is not good that a function call overhead is required when use them. It would be better if we declare them inline and let the compiler do the choice.

We add kernel-offset.c for TASK_RCU_OFFSET, which enable we declare rcu_read_[un]lock() as inline function.

Adding kernel-offset.c does not have any effect for the result compiled kernel, it just adds a small and fast step in the kbuid stage.

Lai Jiangshan (5):
task_rcu_struct
kbuild_dedumplicated
add_kernel_offset
access task's task_rcu_struct without include sched.h rcu inline

 Kbuild                    |   99 ++++++++++++++++---------------
 include/linux/init_task.h |   25 +--------
 include/linux/rcupdate.h  |  144 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/sched.h     |   39 +------------
 kernel/kernel-offsets.c   |   17 +++++
 kernel/rcutiny_plugin.h   |   58 ++++--------------
 kernel/rcutree_plugin.h   |   69 ++++++----------------
 7 files changed, 243 insertions(+), 208 deletions(-)
 create mode 100644 kernel/kernel-offsets.c

1.7.4

Add struct task_rcu_struct to make code clearer and move them to rcupdate.h which help us for code maitainment.

task_rcu_struct(), current_task_rcu_struct(), task_of_task_rcu() and rcu_copy_process() have to be implemented as MACRO,
it is because we cann't access task's task_rcu_strut without linux/sched.h included. These MACROs can only
be used with linux/sched.h included or used in some other MACROs which make this requirement propagate.

---
 include/linux/init_task.h |   25 +----------------
 include/linux/rcupdate.h  |   68 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/sched.h     |   39 +-------------------------
 kernel/rcutiny_plugin.h   |   26 +++++++++--------
 kernel/rcutree_plugin.h   |   37 ++++++++++++------------
 5 files changed, 102 insertions(+), 93 deletions(-)

index caa151f..1749002 100644
@@ -90,29 +90,6 @@ extern struct group_info init_groups;
  */
 # define CAP_INIT_BSET  CAP_FULL_SET
 
-#ifdef CONFIG_RCU_BOOST
-#define INIT_TASK_RCU_BOOST()						\
-	.rcu_boost_mutex = NULL,
-#else
-#define INIT_TASK_RCU_BOOST()
-#endif
-#ifdef CONFIG_TREE_PREEMPT_RCU
-#define INIT_TASK_RCU_TREE_PREEMPT()					\
-	.rcu_blocked_node = NULL,
-#else
-#define INIT_TASK_RCU_TREE_PREEMPT(tsk)
-#endif
-#ifdef CONFIG_PREEMPT_RCU
-#define INIT_TASK_RCU_PREEMPT(tsk)					\
-	.rcu_read_lock_nesting = 0,					\
-	.rcu_read_unlock_special = 0,					\
-	.rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry),		\
-	INIT_TASK_RCU_TREE_PREEMPT()					\
-	INIT_TASK_RCU_BOOST()
-#else
-#define INIT_TASK_RCU_PREEMPT(tsk)
-#endif
-
 extern struct cred init_cred;
 
 #ifdef CONFIG_PERF_EVENTS

@@ -191,7 +168,7 @@ extern struct cred init_cred;
 	INIT_LOCKDEP							\
 	INIT_FTRACE_GRAPH						\
 	INIT_TRACE_RECURSION						\
-	INIT_TASK_RCU_PREEMPT(tsk)					\
+	.task_rcu_struct = INIT_TASK_RCU_STRUCT(tsk.task_rcu_struct),	\
 }
 
 

index 777d8a5..8b359f3 100644
@@ -1232,17 +1232,7 @@ struct task_struct {
 	unsigned int policy;
 	cpumask_t cpus_allowed;
 
-#ifdef CONFIG_PREEMPT_RCU
-	int rcu_read_lock_nesting;
-	char rcu_read_unlock_special;
-	struct list_head rcu_node_entry;
-#endif /* #ifdef CONFIG_PREEMPT_RCU */
-#ifdef CONFIG_TREE_PREEMPT_RCU
-	struct rcu_node *rcu_blocked_node;
-#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
-#ifdef CONFIG_RCU_BOOST
-	struct rt_mutex *rcu_boost_mutex;
-#endif /* #ifdef CONFIG_RCU_BOOST */
+	struct task_rcu_struct task_rcu_struct;
 
 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
 	struct sched_info sched_info;

@@ -1772,33 +1762,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
 #define used_math() tsk_used_math(current)
 
-#ifdef CONFIG_PREEMPT_RCU
-
-#define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
-#define RCU_READ_UNLOCK_BOOSTED (1 << 1) /* boosted while in RCU read-side. */
-#define RCU_READ_UNLOCK_NEED_QS (1 << 2) /* RCU core needs CPU response. */
-
-static inline void rcu_copy_process(struct task_struct *p)
-{
-	p->rcu_read_lock_nesting = 0;
-	p->rcu_read_unlock_special = 0;
-#ifdef CONFIG_TREE_PREEMPT_RCU
-	p->rcu_blocked_node = NULL;
-#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
-#ifdef CONFIG_RCU_BOOST
-	p->rcu_boost_mutex = NULL;
-#endif /* #ifdef CONFIG_RCU_BOOST */
-	INIT_LIST_HEAD(&p->rcu_node_entry);
-}
-
-#else
-
-static inline void rcu_copy_process(struct task_struct *p)
-{
-}
-
-#endif
-
 #ifdef CONFIG_SMP
 extern int set_cpus_allowed_ptr(struct task_struct *p,
 				const struct cpumask *new_mask);

index f259c67..425e892 100644
@@ -150,7 +150,7 @@ static int rcu_cpu_blocking_cur_gp(void)
  */
 static int rcu_preempt_running_reader(void)
 {
-	return current->rcu_read_lock_nesting;
+	return current_task_rcu_struct()->rcu_read_lock_nesting;
 }
 
 /*

@@ -192,7 +192,7 @@ static int rcu_preempt_gp_in_progress(void)
  * Advance a ->blkd_tasks-list pointer to the next entry, instead
  * returning NULL if at the end of the list.
  */
-static struct list_head *rcu_next_node_entry(struct task_struct *t)
+static struct list_head *rcu_next_node_entry(struct task_rcu_struct *t)
 {
 	struct list_head *np;
 

@@ -255,7 +255,7 @@ static int rcu_boost(void)
 {
 	unsigned long flags;
 	struct rt_mutex mtx;
-	struct task_struct *t;
+	struct task_rcu_struct *t;
 	struct list_head *tb;
 
 	if (rcu_preempt_ctrlblk.boost_tasks == NULL &&

@@ -298,8 +298,8 @@ static int rcu_boost(void)
 	 * simply acquiring this artificial rt_mutex will boost task
 	 * t's priority.  (Thanks to tglx for suggesting this approach!)
 	 */
-	t = container_of(tb, struct task_struct, rcu_node_entry);
-	rt_mutex_init_proxy_locked(&mtx, t);
+	t = container_of(tb, struct task_rcu_struct, rcu_node_entry);
+	rt_mutex_init_proxy_locked(&mtx, task_of_task_rcu(t));
 	t->rcu_boost_mutex = &mtx;
 	t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED;
 	raw_local_irq_restore(flags);

@@ -402,9 +402,11 @@ static void rcu_preempt_boost_start_gp(void)
  */
 static void rcu_preempt_cpu_qs(void)
 {
+	struct task_rcu_struct *t = current_task_rcu_struct();
+
 	/* Record both CPU and task as having responded to current GP. */
 	rcu_preempt_ctrlblk.gpcpu = rcu_preempt_ctrlblk.gpnum;
-	current->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
+	t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
 
 	/* If there is no GP then there is nothing more to do.  */
 	if (!rcu_preempt_gp_in_progress())

@@ -473,7 +475,7 @@ static void rcu_preempt_start_gp(void)
  */
 void rcu_preempt_note_context_switch(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 	unsigned long flags;
 
 	local_irq_save(flags); /* must exclude scheduler_tick(). */

@@ -518,7 +520,7 @@ void rcu_preempt_note_context_switch(void)
  */
 void __rcu_read_lock(void)
 {
-	current->rcu_read_lock_nesting++;
+	current_task_rcu_struct()->rcu_read_lock_nesting++;
 	barrier();  /* needed if we ever invoke rcu_read_lock in rcutiny.c */
 }
 EXPORT_SYMBOL_GPL(__rcu_read_lock);

@@ -528,7 +530,7 @@ EXPORT_SYMBOL_GPL(__rcu_read_lock);
  * notify RCU core processing or task having blocked during the RCU
  * read-side critical section.
  */
-static void rcu_read_unlock_special(struct task_struct *t)
+static void rcu_read_unlock_special(struct task_rcu_struct *t)
 {
 	int empty;
 	int empty_exp;

@@ -617,7 +619,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
  */
 void __rcu_read_unlock(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	barrier();  /* needed if we ever invoke rcu_read_unlock in rcutiny.c */
 	--t->rcu_read_lock_nesting;

@@ -640,7 +642,7 @@ EXPORT_SYMBOL_GPL(__rcu_read_unlock);
  */
 static void rcu_preempt_check_callbacks(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	if (rcu_preempt_gp_in_progress() &&
 	    (!rcu_preempt_running_reader() ||

@@ -841,7 +843,7 @@ int rcu_preempt_needs_cpu(void)
  */
 void exit_rcu(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	if (t->rcu_read_lock_nesting == 0)
 		return;

index 6d6079c..88a12d4 100644
@@ -120,11 +120,12 @@ EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
 static void rcu_preempt_qs(int cpu)
 {
 	struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	rdp->passed_quiesc_completed = rdp->gpnum - 1;
 	barrier();
 	rdp->passed_quiesc = 1;
-	current->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
+	t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
 }
 
 /*

@@ -142,7 +143,7 @@ static void rcu_preempt_qs(int cpu)
  */
 static void rcu_preempt_note_context_switch(int cpu)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 	unsigned long flags;
 	struct rcu_data *rdp;
 	struct rcu_node *rnp;

@@ -213,7 +214,7 @@ static void rcu_preempt_note_context_switch(int cpu)
  */
 void __rcu_read_lock(void)
 {
-	current->rcu_read_lock_nesting++;
+	current_task_rcu_struct()->rcu_read_lock_nesting++;
 	barrier();  /* needed if we ever invoke rcu_read_lock in rcutree.c */
 }
 EXPORT_SYMBOL_GPL(__rcu_read_lock);

@@ -268,7 +269,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
  * Advance a ->blkd_tasks-list pointer to the next entry, instead
  * returning NULL if at the end of the list.
  */
-static struct list_head *rcu_next_node_entry(struct task_struct *t,
+static struct list_head *rcu_next_node_entry(struct task_rcu_struct *t,
 					     struct rcu_node *rnp)
 {
 	struct list_head *np;

@@ -284,7 +285,7 @@ static struct list_head *rcu_next_node_entry(struct task_struct *t,
  * notify RCU core processing or task having blocked during the RCU
  * read-side critical section.
  */
-static void rcu_read_unlock_special(struct task_struct *t)
+static void rcu_read_unlock_special(struct task_rcu_struct *t)
 {
 	int empty;
 	int empty_exp;

@@ -384,7 +385,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
  */
 void __rcu_read_unlock(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	barrier();  /* needed if we ever invoke rcu_read_unlock in rcutree.c */
 	--t->rcu_read_lock_nesting;

@@ -407,15 +408,15 @@ EXPORT_SYMBOL_GPL(__rcu_read_unlock);
 static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
 {
 	unsigned long flags;
-	struct task_struct *t;
+	struct task_rcu_struct *t;
 
 	if (!rcu_preempt_blocked_readers_cgp(rnp))
 		return;
 	raw_spin_lock_irqsave(&rnp->lock, flags);
 	t = list_entry(rnp->gp_tasks,
-		       struct task_struct, rcu_node_entry);
+		       struct task_rcu_struct, rcu_node_entry);
 	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
-		sched_show_task(t);
+		sched_show_task(task_of_task_rcu(t));
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 }
 

@@ -446,14 +447,14 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
  */
 static void rcu_print_task_stall(struct rcu_node *rnp)
 {
-	struct task_struct *t;
+	struct task_rcu_struct *t;
 
 	if (!rcu_preempt_blocked_readers_cgp(rnp))
 		return;
 	t = list_entry(rnp->gp_tasks,
-		       struct task_struct, rcu_node_entry);
+		       struct task_rcu_struct, rcu_node_entry);
 	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
-		printk(" P%d", t->pid);
+		printk(" P%d", task_of_task_rcu(t)->pid);
 }
 
 /*

@@ -508,7 +509,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
 	struct list_head *lp_root;
 	int retval = 0;
 	struct rcu_node *rnp_root = rcu_get_root(rsp);
-	struct task_struct *t;
+	struct task_rcu_struct *t;
 
 	if (rnp == rnp_root) {
 		WARN_ONCE(1, "Last CPU thought to be offlined?");

@@ -581,7 +582,7 @@ static void rcu_preempt_offline_cpu(int cpu)
  */
 static void rcu_preempt_check_callbacks(int cpu)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	if (t->rcu_read_lock_nesting == 0) {
 		rcu_preempt_qs(cpu);

@@ -851,7 +852,7 @@ static void __init __rcu_init_preempt(void)
  */
 void exit_rcu(void)
 {
-	struct task_struct *t = current;
+	struct task_rcu_struct *t = current_task_rcu_struct();
 
 	if (t->rcu_read_lock_nesting == 0)
 		return;

@@ -1110,7 +1111,7 @@ static int rcu_boost(struct rcu_node *rnp)
 {
 	unsigned long flags;
 	struct rt_mutex mtx;
-	struct task_struct *t;
+	struct task_rcu_struct *t;
 	struct list_head *tb;
 
 	if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL)

@@ -1158,8 +1159,8 @@ static int rcu_boost(struct rcu_node *rnp)
 	 * and task t's exiting its outermost RCU read-side critical
 	 * section.
 	 */
-	t = container_of(tb, struct task_struct, rcu_node_entry);
-	rt_mutex_init_proxy_locked(&mtx, t);
+	t = container_of(tb, struct task_rcu_struct, rcu_node_entry);
+	rt_mutex_init_proxy_locked(&mtx, task_of_task_rcu(t));
 	t->rcu_boost_mutex = &mtx;
 	t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED;
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);

1.7.4

No good reason. Lai just copied the existing char from the task struct into his task_rcu_struct, so not his fault. ;-)

Thanx, Paul

cmd_bounds and cmd_offsets are almost the same, dedumplicated them. The definition of sed-y is also moved up the top of the file.

---
 Kbuild |   60 +++++++++++++++++++++---------------------------------------
 1 files changed, 21 insertions(+), 39 deletions(-)

index 2114113..5c2ee83 100644
@@ -5,19 +5,19 @@
 # 2) Generate asm-offsets.h (may need bounds.h)
 # 3) Check for missing system calls
 
-#####
-# 1) Generate bounds.h
-
-bounds-file := include/generated/bounds.h
-
-always  := $(bounds-file)
-targets := $(bounds-file) kernel/bounds.s
+# Default sed regexp - multiline due to syntax constraints
+define sed-y
+	"/^->/{s:->#\(.*\):/* \1 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:->::; p;}"
+endef
 
-quiet_cmd_bounds = GEN     $@
-define cmd_bounds
+quiet_cmd_kbuild_gen = GEN     $@
+define cmd_kbuild_gen
 	(set -e; \
-	 echo "#ifndef __LINUX_BOUNDS_H__"; \
-	 echo "#define __LINUX_BOUNDS_H__"; \
+	 echo "#ifndef __$$(echo $@ | tr -- '-./a-z' '___A-Z')__"; \
+	 echo "#define __$$(echo $@ | tr -- '-./a-z' '___A-Z')__"; \
 	 echo "/*"; \
 	 echo " * DO NOT MODIFY."; \
 	 echo " *"; \

@@ -30,6 +30,14 @@ define cmd_bounds
 	 echo "#endif" ) > $@
 endef
 
+#####
+# 1) Generate bounds.h
+
+bounds-file := include/generated/bounds.h
+
+always  := $(bounds-file)
+targets := $(bounds-file) kernel/bounds.s
+
 # We use internal kbuild rules to avoid the "is up to date" message from make
 kernel/bounds.s: kernel/bounds.c FORCE
 	$(Q)mkdir -p $(dir $@)

@@ -37,7 +45,7 @@ kernel/bounds.s: kernel/bounds.c FORCE
 
 $(obj)/$(bounds-file): kernel/bounds.s Kbuild
 	$(Q)mkdir -p $(dir $@)
-	$(call cmd,bounds)
+	$(call cmd,kbuild_gen)
 
 #####
 # 2) Generate asm-offsets.h

@@ -49,32 +57,6 @@ always  += $(offsets-file)
 targets += $(offsets-file)
 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 
-
-# Default sed regexp - multiline due to syntax constraints
-define sed-y
-	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
-quiet_cmd_offsets = GEN     $@
-define cmd_offsets
-	(set -e; \
-	 echo "#ifndef __ASM_OFFSETS_H__"; \
-	 echo "#define __ASM_OFFSETS_H__"; \
-	 echo "/*"; \
-	 echo " * DO NOT MODIFY."; \
-	 echo " *"; \
-	 echo " * This file was generated by Kbuild"; \
-	 echo " *"; \
-	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
-	 echo "#endif" ) > $@
-endef
-
 # We use internal kbuild rules to avoid the "is up to date" message from make
 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
                                       $(obj)/$(bounds-file) FORCE

@@ -82,7 +64,7 @@ arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
 	$(call if_changed_dep,cc_s_c)
 
 $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
-	$(call cmd,offsets)
+	$(call cmd,kbuild_gen)
 
 #####
 # 3) Check for missing system calls

1.7.4

'dedumplicated'? Did you mean 'deduplicated'?

David

Add kernel/kernel-offset.c, include/generated/kernel-offsets.h will be generated from this file and some difines need by kernel is generated in this file.

This generating is assigned as the last step of the kbuild generating, it would require the other earier generated files.

__KBUILD_GENARATING__ is defined when generating, it will be used to avoid compiling errror when generating.

---
 Kbuild                  |   41 ++++++++++++++++++++++++++++++++---------
 kernel/kernel-offsets.c |   14 ++++++++++++++
 2 files changed, 46 insertions(+), 9 deletions(-)

index 5c2ee83..fdfde56 100644
@@ -3,7 +3,8 @@
 # This file takes care of the following:
 # 1) Generate bounds.h
 # 2) Generate asm-offsets.h (may need bounds.h)
-# 3) Check for missing system calls
+# 3) Generate kernel-offsets.h (may need bounds.h and asm-offsets.h)
+# 4) Check for missing system calls
 
 # Default sed regexp - multiline due to syntax constraints
 define sed-y

@@ -30,6 +31,10 @@ define cmd_kbuild_gen
 	 echo "#endif" ) > $@
 endef
 
+quiet_cmd_gen_cc_s_c = CC $(quiet_modtag)  $@
+cmd_gen_cc_s_c       = $(CC) -D__KBUILD_GENARATING__		\
+                       $(c_flags) -fverbose-asm -S -o $@ $<
+
 #####
 # 1) Generate bounds.h
 

@@ -41,7 +46,7 @@ targets := $(bounds-file) kernel/bounds.s
 # We use internal kbuild rules to avoid the "is up to date" message from make
 kernel/bounds.s: kernel/bounds.c FORCE
 	$(Q)mkdir -p $(dir $@)
-	$(call if_changed_dep,cc_s_c)
+	$(call if_changed_dep,gen_cc_s_c)
 
 $(obj)/$(bounds-file): kernel/bounds.s Kbuild
 	$(Q)mkdir -p $(dir $@)

@@ -51,23 +56,41 @@ $(obj)/$(bounds-file): kernel/bounds.s Kbuild
 # 2) Generate asm-offsets.h
 #
 
-offsets-file := include/generated/asm-offsets.h
+asm-offsets-file := include/generated/asm-offsets.h
 
-always  += $(offsets-file)
-targets += $(offsets-file)
+always  += $(asm-offsets-file)
+targets += $(asm-offsets-file)
 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 
 # We use internal kbuild rules to avoid the "is up to date" message from make
 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
                                       $(obj)/$(bounds-file) FORCE
 	$(Q)mkdir -p $(dir $@)
-	$(call if_changed_dep,cc_s_c)
+	$(call if_changed_dep,gen_cc_s_c)
+
+$(obj)/$(asm-offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
+	$(call cmd,kbuild_gen)
+
+#####
+# 3) Generate kernel-offsets.h
+#
+
+kernel-offsets-file := include/generated/kernel-offsets.h
+
+always  += $(kernel-offsets-file)
+targets += $(kernel-offsets-file) kernel/kernel-offsets.s
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+kernel/kernel-offsets.s: kernel/kernel-offsets.c $(obj)/$(asm-offsets-file) \
+                         $(obj)/$(bounds-file) FORCE
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,gen_cc_s_c)
 
-$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
+$(obj)/$(kernel-offsets-file): kernel/kernel-offsets.s Kbuild
 	$(call cmd,kbuild_gen)
 
 #####
-# 3) Check for missing system calls
+# 4) Check for missing system calls
 #
 
 quiet_cmd_syscalls = CALL    $<

@@ -78,4 +101,4 @@ missing-syscalls: scripts/checksyscalls.sh FORCE
 	$(call cmd,syscalls)
 
 # Keep these two files during make clean
-no-clean-files := $(bounds-file) $(offsets-file)
+no-clean-files := $(bounds-file) $(asm-offsets-file) $(kernel-offsets-file)

new file mode 100644
index 0000000..fb73ccf
@@ -0,0 +1,14 @@
+/*
+ * Generate definitions needed by assembly language modules.
+ *
+ * Copyright (C) 2010 Lai Jiangshan
+ */
+
+#include <linux/kbuild.h>
+
+void foo(void);
+
+void foo(void)
+{
+}
+

1.7.4

Should that be __KBUILD_GENERATING__?

David

We can not include linux/sched.h in linux/rcupdate.h. If we access task's task_rcu_strut without linux/sched.h included, We will failed with compiling error.

So we add TASK_RCU_OFFSET, which help us access
task's task_rcu_strut without linux/sched.h included.
Now, task_rcu_struct(), current_task_rcu_struct(), task_of_task_rcu() and rcu_copy_process() can be used anywhere without linux/sched.h included.

---
 include/linux/rcupdate.h |   49 +++++++++++++++++++++++++++++++++++++++++----
 kernel/kernel-offsets.c  |    3 ++
 2 files changed, 47 insertions(+), 5 deletions(-)

index 3500138..a5ed3fe 100644
@@ -140,11 +140,50 @@ static inline void init_task_rcu_struct(struct task_rcu_struct *task_rcu)
 #endif
 }
 
-#define task_rcu_struct(t) (&(t)->task_rcu_struct)
-#define current_task_rcu_struct() task_rcu_struct(current)
-#define task_of_task_rcu(task_rcu) container_of(task_rcu, struct task_struct,\
-				   task_rcu_struct)
-#define rcu_copy_process(tsk) init_task_rcu_struct(task_rcu_struct(tsk))
+#ifdef __KBUILD_GENARATING__
+/*
+ * Very eary kbuild stage, many important defines including TASK_RCU_OFFSET
+ * are not available, use dummies to avoid compiling errors.
+ */
+static inline
+struct task_rcu_struct *task_rcu_struct(struct task_struct *t)
+{
+	(void)t;
+	return (struct task_rcu_struct *)0x3L;
+}
+
+static inline
+struct task_struct *task_of_task_rcu(struct task_rcu_struct *task_rcu)
+{
+	(void)task_rcu;
+	return (struct task_struct *)-0x3L;
+}
+#else
+/* for generated TASK_RCU_OFFSET */
+#include <generated/kernel-offsets.h>
+
+static inline
+struct task_rcu_struct *task_rcu_struct(struct task_struct *t)
+{
+	return (struct task_rcu_struct *)(((void *)t) + TASK_RCU_OFFSET);
+}
+
+static inline
+struct task_struct *task_of_task_rcu(struct task_rcu_struct *task_rcu)
+{
+	return (struct task_struct *)(((void *)task_rcu) - TASK_RCU_OFFSET);
+}
+#endif
+
+static inline struct task_rcu_struct *current_task_rcu_struct(void)
+{
+	return task_rcu_struct(current);
+}
+
+static inline void rcu_copy_process(struct task_struct *tsk)
+{
+	init_task_rcu_struct(task_rcu_struct(tsk));
+}
 
 #ifdef CONFIG_PREEMPT_RCU
 

index fb73ccf..a890511 100644
@@ -4,11 +4,14 @@
  * Copyright (C) 2010 Lai Jiangshan
  */
 
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
 #include <linux/kbuild.h>
 
 void foo(void);
 
 void foo(void)
 {
+	OFFSET(TASK_RCU_OFFSET, task_struct, task_rcu_struct);
 }
 

1.7.4

Aren't the offsets-generation methods meant for assembly consumption only? Header dependency problems normally can be solved by splitting headers into a type declaration one and a second one carrying inline function implementations. Is that indeed completely impossible here?

Jan

That will need to split >100 header files, it is almost impossible.

Thanks,
Lai

I have to say that if we have to use hardcoded offsets in C then we have bigger problems.

-hpa

In this case, the offsets are mechanically generated from the structure definitions.

Or am I missing your point?

Thanx, Paul

Yes. The point is if we have to pull out these kinds of hacks in *C* code, we are doing it wrong. Not just a little wrong, but completely and totally bonkers wrong.

-hpa

OK, maybe we are doing it wrong.

But in that case, how do you suggest restructuring include/linux/sched.h so that struct task_struct can be safely included everywhere rcu_read_lock() and friends are invoked? Or, on the other hand, what should we be doing so that we don't need to include task_struct everywhere?

Thanx, Paul

Lai's text doesn't give any hint as to the specific nature of the conflict, which makes it hard to come up with a better alternative without having to rediscover the problem from first principles. However, a somewhat logical assumption is that the problem is that struct task_struct includes struct rcu_head, in which case the easiest thing to do is almost certainly to move the definition of struct rcu_head to its own header file, <linux/rcuhead.h>, and include that in <linux/sched.h>, which should make it possible to include <linux/sched.h> in <linux/rcupdate.h>.

-hpa

I believe that there are other circular dependencies -- there certainly were a few years back -- but I will defer to Lai.

Thanx, Paul

Yes, there are other circular dependencies, <linux/sched.h> includes many files which include or indirectly include <linux/rcupdate.h> for struct rcu_head or RCU apis. There are too many to be split all.

Even we just create a <linux/task_struct_def.h>, it also needs to include many files which have included or indirectly included <linux/rcupdate.h> for struct rcu_head already. It is still not a easy work to split them, it still requires many subsystem maintainers to participate in.

RCU is one of the most import subsystem,
I think it is worth to do such "wrong" way.

Thanks,
Lai

P.S.

Circular dependencies is one of the original sins of C language. If it is a good change for lots of linux hackers participating in to split all un-split kernel headers, I'd like to do so too.

<linux/rcupdate.h> is so generic that it is included in many headers. <linux/sched.h> is so complex that it includes many headers.

How many files which include(or indirectly include) <linux/rcupdate.h> are included(or indirectly included) by <linux/sched.h>?

714 files! So I can guess 100 files at least is needed to be touched if we resolve this problem by splitting.

include/linux/sched.h
include/linux/kernel.h
include/linux/timex.h
include/linux/jiffies.h
include/linux/rbtree.h
include/linux/thread_info.h
include/linux/cpumask.h
include/linux/nodemask.h
include/linux/mm_types.h
arch/alpha/include/asm/system.h
arch/arm/include/asm/system.h
arch/avr32/include/asm/system.h
arch/blackfin/include/asm/system.h
arch/cris/include/asm/system.h
arch/frv/include/asm/system.h
arch/h8300/include/asm/system.h
arch/ia64/include/asm/system.h
arch/m32r/include/asm/system.h
arch/microblaze/include/asm/system.h
arch/mips/include/asm/system.h
arch/mn10300/include/asm/system.h
arch/parisc/include/asm/system.h
arch/powerpc/include/asm/system.h
arch/s390/include/asm/system.h
arch/score/include/asm/system.h
arch/sh/include/asm/system.h
arch/sparc/include/asm/system.h
arch/tile/include/asm/system.h
arch/unicore32/include/asm/system.h
arch/x86/include/asm/system.h
arch/xtensa/include/asm/system.h
arch/mips/include/asm/page.h
arch/sh/include/asm/page.h
arch/powerpc/include/asm/ptrace.h
arch/sh/include/asm/ptrace.h
arch/sparc/include/asm/ptrace.h
arch/alpha/include/asm/cputime.h
arch/arm/include/asm/cputime.h
arch/avr32/include/asm/cputime.h
arch/blackfin/include/asm/cputime.h
arch/cris/include/asm/cputime.h
arch/frv/include/asm/cputime.h
arch/h8300/include/asm/cputime.h
arch/ia64/include/asm/cputime.h
arch/m32r/include/asm/cputime.h
arch/m68k/include/asm/cputime.h
arch/microblaze/include/asm/cputime.h
arch/mips/include/asm/cputime.h
arch/mn10300/include/asm/cputime.h
arch/parisc/include/asm/cputime.h
arch/powerpc/include/asm/cputime.h
arch/s390/include/asm/cputime.h
arch/score/include/asm/cputime.h
arch/sh/include/asm/cputime.h
arch/sparc/include/asm/cputime.h
arch/tile/include/asm/cputime.h
arch/um/include/asm/cputime.h
arch/x86/include/asm/cputime.h
arch/xtensa/include/asm/cputime.h
include/linux/smp.h
include/linux/sem.h
include/linux/signal.h
include/linux/completion.h
include/linux/pid.h
include/linux/percpu.h
include/linux/topology.h
include/linux/proportions.h
include/linux/seccomp.h
include/linux/rculist.h
include/linux/rtmutex.h
include/linux/time.h
include/linux/resource.h
include/linux/timer.h
include/linux/hrtimer.h
include/linux/cred.h
arch/cris/include/asm/processor.h
arch/h8300/include/asm/processor.h
arch/ia64/include/asm/processor.h
arch/m32r/include/asm/processor.h
arch/m68k/include/asm/processor.h
arch/mips/include/asm/processor.h
arch/mn10300/include/asm/processor.h
arch/parisc/include/asm/processor.h
arch/powerpc/include/asm/processor.h
arch/score/include/asm/processor.h
arch/sparc/include/asm/processor.h
arch/x86/include/asm/processor.h
include/linux/spinlock.h
include/linux/aio.h
arch/alpha/include/asm/current.h
arch/arm/include/asm/current.h
arch/avr32/include/asm/current.h
arch/blackfin/include/asm/current.h
arch/cris/include/asm/current.h
arch/h8300/include/asm/current.h
arch/m32r/include/asm/current.h
arch/m68k/include/asm/current.h
arch/mips/include/asm/current.h
arch/mn10300/include/asm/current.h
arch/parisc/include/asm/current.h
arch/powerpc/include/asm/current.h
arch/score/include/asm/current.h
arch/sh/include/asm/current.h
arch/sparc/include/asm/current.h
arch/tile/include/asm/current.h
arch/x86/include/asm/current.h
arch/xtensa/include/asm/current.h
include/linux/bitops.h
include/linux/log2.h
arch/s390/include/asm/bug.h
arch/arm/include/asm/div64.h
arch/ia64/include/asm/timex.h
arch/mips/include/asm/timex.h
arch/mn10300/include/asm/timex.h
arch/parisc/include/asm/timex.h
arch/sparc/include/asm/timex.h
arch/x86/include/asm/timex.h
include/linux/math64.h
arch/cris/include/asm/thread_info.h
arch/ia64/include/asm/thread_info.h
arch/m32r/include/asm/thread_info.h
arch/m68k/include/asm/thread_info.h
arch/mips/include/asm/thread_info.h
arch/parisc/include/asm/thread_info.h
arch/powerpc/include/asm/thread_info.h
arch/score/include/asm/thread_info.h
arch/sh/include/asm/thread_info.h
arch/sparc/include/asm/thread_info.h
arch/x86/include/asm/thread_info.h
include/linux/bitmap.h
include/linux/list.h
include/linux/rwsem.h
arch/sh/include/asm/mmu.h
arch/x86/include/asm/mmu.h
include/linux/irqflags.h
include/asm-generic/cmpxchg-local.h
arch/blackfin/include/asm/irq.h
arch/mips/include/asm/cmpxchg.h
arch/mips/include/asm/dsp.h
arch/mips/include/asm/watch.h
arch/mn10300/include/asm/atomic.h
arch/powerpc/include/asm/hw_irq.h
arch/sh/include/asm/uncached.h
arch/sparc/include/asm/system_64.h
arch/sparc/include/asm/system_32.h
arch/x86/include/asm/cpufeature.h
arch/x86/include/asm/paravirt.h
arch/mips/include/asm/io.h
include/asm-generic/cputime.h
arch/powerpc/include/asm/time.h
include/linux/preempt.h
arch/alpha/include/asm/smp.h
arch/arm/include/asm/smp.h
arch/blackfin/include/asm/smp.h
arch/cris/include/asm/smp.h
arch/ia64/include/asm/smp.h
arch/m32r/include/asm/smp.h
arch/mips/include/asm/smp.h
arch/mn10300/include/asm/smp.h
arch/parisc/include/asm/smp.h
arch/powerpc/include/asm/smp.h
arch/s390/include/asm/smp.h
arch/sh/include/asm/smp.h
arch/sparc/include/asm/smp.h
arch/tile/include/asm/smp.h
arch/x86/include/asm/smp.h
include/linux/ipc.h
arch/alpha/include/asm/atomic.h
arch/arm/include/asm/atomic.h
arch/avr32/include/asm/atomic.h
arch/blackfin/include/asm/atomic.h
arch/cris/include/asm/atomic.h
arch/frv/include/asm/atomic.h
arch/h8300/include/asm/atomic.h
arch/ia64/include/asm/atomic.h
arch/m32r/include/asm/atomic.h
arch/microblaze/include/asm/atomic.h
arch/mips/include/asm/atomic.h
arch/parisc/include/asm/atomic.h
arch/powerpc/include/asm/atomic.h
arch/s390/include/asm/atomic.h
arch/score/include/asm/atomic.h
arch/sh/include/asm/atomic.h
arch/sparc/include/asm/atomic.h
arch/tile/include/asm/atomic.h
arch/x86/include/asm/atomic.h
arch/xtensa/include/asm/atomic.h
include/linux/cache.h
arch/blackfin/include/asm/signal.h
arch/frv/include/asm/signal.h
arch/m32r/include/asm/signal.h
arch/microblaze/include/asm/signal.h
arch/s390/include/asm/signal.h
arch/score/include/asm/signal.h
arch/sh/include/asm/signal.h
arch/sparc/include/asm/signal.h
arch/tile/include/asm/signal.h
arch/x86/include/asm/signal.h
arch/sparc/include/asm/siginfo.h
include/linux/wait.h
arch/powerpc/include/asm/percpu.h
arch/x86/include/asm/percpu.h
include/linux/mmzone.h
arch/alpha/include/asm/topology.h
arch/ia64/include/asm/topology.h
arch/powerpc/include/asm/topology.h
arch/s390/include/asm/topology.h
arch/sparc/include/asm/topology.h
arch/tile/include/asm/topology.h
arch/x86/include/asm/topology.h
include/linux/percpu_counter.h
include/linux/mutex.h
include/linux/plist.h
include/linux/spinlock_types.h
include/linux/seqlock.h
include/linux/ktime.h
include/linux/debugobjects.h
include/linux/timerqueue.h
include/linux/key.h
arch/mips/include/asm/mipsregs.h
arch/mn10300/include/asm/uaccess.h
arch/sparc/include/asm/processor_64.h
arch/sparc/include/asm/processor_32.h
arch/x86/include/asm/msr.h
arch/alpha/include/asm/spinlock.h
arch/blackfin/include/asm/spinlock.h
arch/ia64/include/asm/spinlock.h
arch/m32r/include/asm/spinlock.h
arch/mn10300/include/asm/spinlock.h
arch/parisc/include/asm/spinlock.h
arch/powerpc/include/asm/spinlock.h
arch/s390/include/asm/spinlock.h
arch/tile/include/asm/spinlock.h
arch/x86/include/asm/spinlock.h
arch/xtensa/include/asm/spinlock.h
include/linux/workqueue.h
include/asm-generic/current.h
arch/powerpc/include/asm/paca.h
arch/arm/include/asm/bitops.h
arch/avr32/include/asm/bitops.h
arch/blackfin/include/asm/bitops.h
arch/cris/include/asm/bitops.h
arch/h8300/include/asm/bitops.h
arch/m32r/include/asm/bitops.h
arch/microblaze/include/asm/bitops.h
arch/mips/include/asm/bitops.h
arch/parisc/include/asm/bitops.h
arch/score/include/asm/bitops.h
arch/sh/include/asm/bitops.h
arch/tile/include/asm/bitops.h
arch/unicore32/include/asm/bitops.h
arch/x86/include/asm/bitops.h
arch/xtensa/include/asm/bitops.h
arch/mn10300/include/asm/hardirq.h
arch/sparc/include/asm/timex_64.h
arch/x86/include/asm/tsc.h
arch/sparc/include/asm/thread_info_64.h
arch/sparc/include/asm/thread_info_32.h
include/linux/prefetch.h
arch/alpha/include/asm/irqflags.h
arch/m68k/include/asm/irqflags.h
arch/mn10300/include/asm/irqflags.h
arch/powerpc/include/asm/irqflags.h
arch/x86/include/asm/irqflags.h
include/asm-generic/atomic.h
include/linux/bug.h
arch/sparc/include/asm/visasm.h
arch/powerpc/include/asm/iseries/hv_call.h
arch/ia64/include/asm/io.h
arch/mips/include/asm/smp-ops.h
arch/s390/include/asm/sigp.h
arch/sparc/include/asm/smp_64.h
arch/sparc/include/asm/smp_32.h
arch/x86/include/asm/apic.h
arch/x86/include/asm/cpumask.h
arch/sparc/include/asm/atomic_64.h
arch/sparc/include/asm/atomic_32.h
arch/x86/include/asm/alternative.h
include/asm-generic/signal.h
arch/sparc/include/asm/sigcontext.h
include/linux/compat.h
include/linux/memory_hotplug.h
arch/alpha/include/asm/mmzone.h
arch/m32r/include/asm/mmzone.h
arch/mips/include/asm/mmzone.h
arch/powerpc/include/asm/mmzone.h
arch/sparc/include/asm/mmzone.h
arch/ia64/include/asm/acpi.h
arch/ia64/include/asm/numa.h
arch/sparc/include/asm/topology_64.h
include/linux/lockdep.h
include/linux/mutex-debug.h
include/linux/sysctl.h
arch/tile/include/asm/spinlock_32.h
arch/powerpc/include/asm/lppaca.h
include/asm-generic/bitops/atomic.h
include/asm-generic/bitops.h
arch/tile/include/asm/bitops_32.h
include/linux/irq.h
arch/sparc/include/asm/timer.h
include/linux/hardirq.h
arch/ia64/include/asm/unaligned.h
include/linux/delay.h
include/linux/pm.h
arch/x86/include/asm/fixmap.h
arch/powerpc/include/asm/sigcontext.h
include/linux/stat.h
arch/mips/include/asm/compat.h
arch/parisc/include/asm/compat.h
arch/powerpc/include/asm/compat.h
arch/s390/include/asm/compat.h
arch/tile/include/asm/compat.h
arch/x86/include/asm/compat.h
include/linux/notifier.h
include/linux/debug_locks.h
include/linux/gfp.h
include/linux/irqnr.h
arch/ia64/include/asm/irq.h
arch/m68k/include/asm/irq.h
arch/mips/include/asm/irq.h
arch/parisc/include/asm/irq.h
arch/powerpc/include/asm/irq.h
arch/s390/include/asm/irq.h
arch/sh/include/asm/irq.h
arch/sparc/include/asm/irq.h
arch/tile/include/asm/irq.h
arch/x86/include/asm/irq.h
arch/alpha/include/asm/irq_regs.h
arch/arm/include/asm/irq_regs.h
arch/avr32/include/asm/irq_regs.h
arch/blackfin/include/asm/irq_regs.h
arch/cris/include/asm/irq_regs.h
arch/h8300/include/asm/irq_regs.h
arch/ia64/include/asm/irq_regs.h
arch/m32r/include/asm/irq_regs.h
arch/m68k/include/asm/irq_regs.h
arch/microblaze/include/asm/irq_regs.h
arch/mips/include/asm/irq_regs.h
arch/parisc/include/asm/irq_regs.h
arch/powerpc/include/asm/irq_regs.h
arch/s390/include/asm/irq_regs.h
arch/score/include/asm/irq_regs.h
arch/sh/include/asm/irq_regs.h
arch/sparc/include/asm/irq_regs.h
arch/tile/include/asm/irq_regs.h
arch/um/include/asm/irq_regs.h
arch/x86/include/asm/irq_regs.h
arch/xtensa/include/asm/irq_regs.h
arch/ia64/include/asm/hw_irq.h
arch/mips/include/asm/hw_irq.h
arch/sh/include/asm/hw_irq.h
arch/x86/include/asm/hw_irq.h
arch/sparc/include/asm/timer_32.h
arch/alpha/include/asm/hardirq.h
arch/arm/include/asm/hardirq.h
arch/avr32/include/asm/hardirq.h
arch/blackfin/include/asm/hardirq.h
arch/cris/include/asm/hardirq.h
arch/frv/include/asm/hardirq.h
arch/h8300/include/asm/hardirq.h
arch/ia64/include/asm/hardirq.h
arch/m32r/include/asm/hardirq.h
arch/microblaze/include/asm/hardirq.h
arch/mips/include/asm/hardirq.h
arch/parisc/include/asm/hardirq.h
arch/powerpc/include/asm/hardirq.h
arch/score/include/asm/hardirq.h
arch/sh/include/asm/hardirq.h
arch/sparc/include/asm/hardirq.h
arch/tile/include/asm/hardirq.h
arch/um/include/asm/hardirq.h
arch/x86/include/asm/hardirq.h
arch/xtensa/include/asm/hardirq.h
include/linux/unaligned/le_struct.h
arch/ia64/include/asm/delay.h
arch/parisc/include/asm/delay.h
arch/powerpc/include/asm/delay.h
arch/sparc/include/asm/delay.h
arch/x86/include/asm/acpi.h
arch/x86/include/asm/vsyscall.h
arch/powerpc/include/asm/elf.h
include/linux/srcu.h
arch/mips/include/asm/mipsmtregs.h
include/linux/radix-tree.h
arch/sh/include/asm/machvec.h
arch/sparc/include/asm/irq_64.h
arch/sparc/include/asm/irq_32.h
include/asm-generic/irq_regs.h
include/linux/interrupt.h
include/linux/profile.h
arch/ia64/include/asm/paravirt.h
arch/x86/include/asm/sections.h
include/asm-generic/hardirq.h
arch/sparc/include/asm/hardirq_64.h
arch/sparc/include/asm/hardirq_32.h
include/linux/unaligned/packed_struct.h
arch/sparc/include/asm/delay_32.h
arch/x86/include/asm/numa.h
arch/x86/include/asm/trampoline.h
include/trace/events/irq.h
arch/x86/include/asm/uaccess.h
arch/sparc/include/asm/cpudata.h
arch/x86/include/asm/io.h
include/linux/tracepoint.h
include/trace/define_trace.h
arch/sparc/include/asm/cpudata_64.h
arch/sparc/include/asm/cpudata_32.h
include/xen/xen.h
include/linux/vmalloc.h
include/linux/module.h
include/trace/ftrace.h
arch/ia64/include/asm/xen/hypervisor.h
arch/x86/include/asm/xen/hypervisor.h
include/linux/kmod.h
include/linux/elf.h
include/linux/kobject.h
include/linux/moduleparam.h
arch/mips/include/asm/module.h
arch/powerpc/include/asm/module.h
arch/score/include/asm/module.h
include/trace/events/module.h
include/linux/ftrace_event.h
arch/mn10300/include/asm/elf.h
arch/s390/include/asm/elf.h
arch/score/include/asm/elf.h
arch/sh/include/asm/elf.h
arch/sparc/include/asm/elf.h
arch/tile/include/asm/elf.h
arch/x86/include/asm/elf.h
include/linux/sysfs.h
arch/mips/include/asm/uaccess.h
arch/score/include/asm/uaccess.h
include/linux/ring_buffer.h
include/linux/trace_seq.h
include/linux/perf_event.h
include/linux/utsname.h
arch/mn10300/include/asm/user.h
arch/s390/include/asm/mmu_context.h
include/linux/ptrace.h
arch/sh/include/asm/user.h
arch/sparc/include/asm/elf_64.h
arch/sparc/include/asm/elf_32.h
arch/x86/include/asm/desc.h
include/linux/kmemcheck.h
include/linux/mm.h
include/linux/seq_file.h
include/linux/fs.h
include/linux/cgroup.h
arch/powerpc/include/asm/perf_event.h
arch/sparc/include/asm/perf_event.h
arch/x86/include/asm/perf_event.h
arch/alpha/include/asm/local64.h
arch/arm/include/asm/local64.h
arch/avr32/include/asm/local64.h
arch/blackfin/include/asm/local64.h
arch/cris/include/asm/local64.h
arch/frv/include/asm/local64.h
arch/h8300/include/asm/local64.h
arch/ia64/include/asm/local64.h
arch/m32r/include/asm/local64.h
arch/m68k/include/asm/local64.h
arch/microblaze/include/asm/local64.h
arch/mips/include/asm/local64.h
arch/mn10300/include/asm/local64.h
arch/parisc/include/asm/local64.h
arch/powerpc/include/asm/local64.h
arch/s390/include/asm/local64.h
arch/score/include/asm/local64.h
arch/sh/include/asm/local64.h
arch/sparc/include/asm/local64.h
arch/x86/include/asm/local64.h
arch/xtensa/include/asm/local64.h
arch/powerpc/include/asm/hw_breakpoint.h
arch/sh/include/asm/hw_breakpoint.h
arch/x86/include/asm/hw_breakpoint.h
include/linux/pid_namespace.h
include/linux/ftrace.h
include/linux/cpu.h
include/linux/jump_label_ref.h
arch/alpha/include/asm/local.h
arch/arm/include/asm/local.h
arch/avr32/include/asm/local.h
arch/blackfin/include/asm/local.h
arch/cris/include/asm/local.h
arch/frv/include/asm/local.h
arch/h8300/include/asm/local.h
arch/ia64/include/asm/local.h
arch/m32r/include/asm/local.h
arch/m68k/include/asm/local.h
arch/microblaze/include/asm/local.h
arch/mips/include/asm/local.h
arch/mn10300/include/asm/local.h
arch/parisc/include/asm/local.h
arch/powerpc/include/asm/local.h
arch/s390/include/asm/local.h
arch/score/include/asm/local.h
arch/sh/include/asm/local.h
arch/sparc/include/asm/local.h
arch/tile/include/asm/local.h
arch/x86/include/asm/local.h
arch/xtensa/include/asm/local.h
include/linux/nsproxy.h
arch/s390/include/asm/pgalloc.h
arch/s390/include/asm/uaccess.h
arch/s390/include/asm/tlbflush.h
arch/sparc/include/asm/uaccess.h
arch/sparc/include/asm/mbus.h
include/linux/bit_spinlock.h
arch/alpha/include/asm/pgtable.h
arch/arm/include/asm/pgtable.h
arch/avr32/include/asm/pgtable.h
arch/blackfin/include/asm/pgtable.h
arch/cris/include/asm/pgtable.h
arch/frv/include/asm/pgtable.h
arch/h8300/include/asm/pgtable.h
arch/ia64/include/asm/pgtable.h
arch/m32r/include/asm/pgtable.h
arch/microblaze/include/asm/pgtable.h
arch/mips/include/asm/pgtable.h
arch/mn10300/include/asm/pgtable.h
arch/parisc/include/asm/pgtable.h
arch/powerpc/include/asm/pgtable.h
arch/s390/include/asm/pgtable.h
arch/score/include/asm/pgtable.h
arch/sh/include/asm/pgtable.h
arch/sparc/include/asm/pgtable.h
arch/tile/include/asm/pgtable.h
arch/um/include/asm/pgtable.h
arch/unicore32/include/asm/pgtable.h
arch/x86/include/asm/pgtable.h
arch/xtensa/include/asm/pgtable.h
include/linux/page-flags.h
include/linux/vmstat.h
include/linux/dcache.h
include/linux/semaphore.h
include/linux/rculist_bl.h
include/linux/quota.h
include/linux/nfs_fs_i.h
include/linux/prio_heap.h
include/linux/idr.h
arch/powerpc/include/asm/perf_event_server.h
arch/powerpc/include/asm/perf_event_fsl_emb.h
arch/x86/include/asm/stacktrace.h
include/asm-generic/local64.h
include/linux/kdebug.h
include/linux/kallsyms.h
arch/blackfin/include/asm/ftrace.h
include/linux/sysdev.h
include/linux/node.h
include/asm-generic/local.h
arch/sparc/include/asm/uaccess_64.h
arch/sparc/include/asm/uaccess_32.h
arch/sparc/include/asm/viking.h
include/asm-generic/pgtable.h
include/linux/slab.h
arch/ia64/include/asm/cacheflush.h
arch/ia64/include/asm/mmu_context.h
arch/mips/include/asm/pgtable-32.h
arch/mips/include/asm/pgtable-64.h
arch/powerpc/include/asm/pgtable-ppc64.h
arch/powerpc/include/asm/pgtable-ppc32.h
arch/sh/include/asm/fixmap.h
arch/sh/include/asm/pgtable_64.h
arch/sparc/include/asm/pgtable_64.h
arch/sparc/include/asm/pgtable_32.h
arch/tile/include/asm/fixmap.h
include/linux/list_bl.h
include/linux/uaccess.h
arch/mips/include/asm/kdebug.h
arch/sparc/include/asm/kdebug.h
arch/x86/include/asm/kdebug.h
arch/sparc/include/asm/pgtsrmmu.h
include/linux/slub_def.h
include/linux/slab_def.h
arch/mips/include/asm/fixmap.h
arch/powerpc/include/asm/tlbflush.h
arch/powerpc/include/asm/io.h
include/linux/swap.h
arch/sparc/include/asm/oplib.h
arch/alpha/include/asm/uaccess.h
arch/arm/include/asm/uaccess.h
arch/avr32/include/asm/uaccess.h
arch/blackfin/include/asm/uaccess.h
arch/cris/include/asm/uaccess.h
arch/frv/include/asm/uaccess.h
arch/h8300/include/asm/uaccess.h
arch/ia64/include/asm/uaccess.h
arch/m32r/include/asm/uaccess.h
arch/microblaze/include/asm/uaccess.h
arch/parisc/include/asm/uaccess.h
arch/powerpc/include/asm/uaccess.h
arch/sh/include/asm/uaccess.h
arch/tile/include/asm/uaccess.h
arch/unicore32/include/asm/uaccess.h
arch/xtensa/include/asm/uaccess.h
arch/sparc/include/asm/kdebug_32.h
include/trace/events/kmem.h
include/linux/device.h
include/linux/io.h
arch/powerpc/include/asm/eeh.h
include/linux/memcontrol.h
arch/sparc/include/asm/oplib_64.h
arch/sparc/include/asm/oplib_32.h
include/asm-generic/uaccess.h
arch/sparc/include/asm/openprom.h
include/linux/klist.h
arch/sparc/include/asm/device.h
arch/alpha/include/asm/io.h
arch/arm/include/asm/io.h
arch/avr32/include/asm/io.h
arch/blackfin/include/asm/io.h
arch/cris/include/asm/io.h
arch/frv/include/asm/io.h
arch/microblaze/include/asm/io.h
arch/mn10300/include/asm/io.h
arch/parisc/include/asm/io.h
arch/score/include/asm/io.h
arch/sh/include/asm/io.h
arch/sparc/include/asm/io.h
arch/tile/include/asm/io.h
arch/unicore32/include/asm/io.h
arch/xtensa/include/asm/io.h
arch/xtensa/include/asm/segment.h
include/linux/of.h
arch/alpha/include/asm/core_lca.h
arch/alpha/include/asm/core_marvel.h
arch/alpha/include/asm/core_t2.h
include/asm-generic/io.h
arch/mn10300/include/asm/cacheflush.h
arch/sh/include/asm/io_trapped.h
arch/sparc/include/asm/io_64.h
arch/sparc/include/asm/io_32.h
arch/microblaze/include/asm/prom.h
arch/powerpc/include/asm/prom.h
arch/sparc/include/asm/prom.h
arch/x86/include/asm/prom.h
arch/alpha/include/asm/cacheflush.h
arch/arm/include/asm/cacheflush.h
arch/avr32/include/asm/cacheflush.h
arch/blackfin/include/asm/cacheflush.h
arch/cris/include/asm/cacheflush.h
arch/frv/include/asm/cacheflush.h
arch/m32r/include/asm/cacheflush.h
arch/microblaze/include/asm/cacheflush.h
arch/mips/include/asm/cacheflush.h
arch/parisc/include/asm/cacheflush.h
arch/powerpc/include/asm/cacheflush.h
arch/s390/include/asm/cacheflush.h
arch/score/include/asm/cacheflush.h
arch/sh/include/asm/cacheflush.h
arch/sparc/include/asm/cacheflush.h
arch/tile/include/asm/cacheflush.h
arch/unicore32/include/asm/cacheflush.h
arch/x86/include/asm/cacheflush.h
arch/xtensa/include/asm/cacheflush.h
include/linux/of_irq.h
include/linux/platform_device.h
include/linux/of_address.h
include/linux/proc_fs.h
include/linux/pci.h
include/asm-generic/cacheflush.h
arch/sparc/include/asm/cacheflush_64.h
arch/sparc/include/asm/cacheflush_32.h
include/linux/dmapool.h
arch/alpha/include/asm/pci.h
arch/arm/include/asm/pci.h
arch/avr32/include/asm/pci.h
arch/blackfin/include/asm/pci.h
arch/cris/include/asm/pci.h
arch/frv/include/asm/pci.h
arch/ia64/include/asm/pci.h
arch/m68k/include/asm/pci.h
arch/microblaze/include/asm/pci.h
arch/mips/include/asm/pci.h
arch/mn10300/include/asm/pci.h
arch/parisc/include/asm/pci.h
arch/powerpc/include/asm/pci.h
arch/sh/include/asm/pci.h
arch/sparc/include/asm/pci.h
arch/tile/include/asm/pci.h
arch/unicore32/include/asm/pci.h
arch/x86/include/asm/pci.h
arch/xtensa/include/asm/pci.h
arch/powerpc/include/asm/scatterlist.h
include/linux/dma-mapping.h
include/asm-generic/pci-dma-compat.h
arch/microblaze/include/asm/pci-bridge.h
arch/powerpc/include/asm/machdep.h
arch/powerpc/include/asm/pci-bridge.h
arch/sparc/include/asm/pci_64.h
arch/sparc/include/asm/pci_32.h
arch/powerpc/include/asm/dma.h
include/linux/dma-attrs.h
include/linux/scatterlist.h
arch/alpha/include/asm/dma-mapping.h
arch/arm/include/asm/dma-mapping.h
arch/avr32/include/asm/dma-mapping.h
arch/blackfin/include/asm/dma-mapping.h
arch/cris/include/asm/dma-mapping.h
arch/frv/include/asm/dma-mapping.h
arch/ia64/include/asm/dma-mapping.h
arch/microblaze/include/asm/dma-mapping.h
arch/mips/include/asm/dma-mapping.h
arch/mn10300/include/asm/dma-mapping.h
arch/parisc/include/asm/dma-mapping.h
arch/powerpc/include/asm/dma-mapping.h
arch/sh/include/asm/dma-mapping.h
arch/sparc/include/asm/dma-mapping.h
arch/tile/include/asm/dma-mapping.h
arch/unicore32/include/asm/dma-mapping.h
arch/x86/include/asm/dma-mapping.h
arch/xtensa/include/asm/dma-mapping.h
include/asm-generic/dma-mapping-common.h
arch/ia64/include/asm/swiotlb.h

#!/bin/python

import re
include_re = re.compile(r'#\s*include\s*<([_\-\w]*)([/\._\-\w]*)>') leaf_file = ('linux', '/rcupdate.h')
archs_dir = (
'arch/alpha/',
'arch/arm/',
'arch/avr32/',
'arch/blackfin/',
'arch/cris/',
'arch/frv/',
'arch/h8300/',
'arch/ia64/',
'arch/m32r/',
'arch/m68k/',
'arch/m68knommu/',
'arch/microblaze/',
'arch/mips/',
'arch/mn10300/',
'arch/parisc/',
'arch/powerpc/',
'arch/s390/',
'arch/score/',
'arch/sh/',
'arch/sparc/',
'arch/tile/',
'arch/um/',
'arch/unicore32/',
'arch/x86/',
'arch/xtensa/',
)

generic_dir = 'include/'
searched = {('include/linux','/rcupdate.h'):1}
searchqueue = []

def add(f):
if searched.has_key(f):
return
searched[f] = 0
searchqueue.append(f)

def addall():
i = 0
while i < len(searchqueue):

    f=searchqueue[i]
    i=i+1
    try:
      ff = file(f[0]+f[1])
    except:
      continue
    for ch in include_re.findall(ff.read()):
      if ch[0] == 'asm':
        if f[0][0:4] == 'arch':
          add((f[0], ch[1]))
          continue
        for dir in archs_dir:
          add((dir+'include/asm', ch[1]))
      else:
        add((generic_dir+ch[0], ch[1]))

def markall():
for f in searchqueue:

    res = 0
    try:
      ff = file(f[0]+f[1])
    except:
      continue
    for ch in include_re.findall(ff.read()):
      if ch[0] == 'asm':
        if f[0][0:4] == 'arch':
          res = res or searched[(f[0], ch[1])]
          continue
        for dir in archs_dir:
          res = res or searched[(dir+'include/asm', ch[1])]
      else:
        res = res or searched[(generic_dir+ch[0], ch[1])]
    searched[f]=res

add(('include/linux', '/sched.h'))
addall()
# I'm lazy to build a map and the reverse map..., thousands of headers is not

# too much for this. add enough markall() until the result output is not changed
markall()
markall()
markall()
markall()
markall()
markall()
markall()
markall()
markall()
markall()
markall()
#markall()
#print len(searchqueue)
for f in searchqueue:
  if searched[f]:
    print f[0]+f[1]

It goes down quickly if you start reducing the dependencies. I wrote a quick&dirty patch that splits 9 headers and the preprocessed result of #include <linux/sched_types.h> is about 7800 lines. Most of it is caused by linux/signal.h which I skipped. What do you think?

Michal

Subject: [PATCH] headers: Allow for lightweight inclusion of task_struct definition

Factor out a couple of type definitions to <header>_types.h to allow using task_struct without pulling tons of new dependencies via sched.h.

---
 include/linux/Kbuild               |    1 +
 include/linux/mutex.h              |   18 +--
 include/linux/mutex_types.h        |   22 ++
 include/linux/nodemask.h           |    2 +-
 include/linux/nodemask_types.h     |   11 +
 include/linux/pid.h                |   15 +-
 include/linux/pid_types.h          |   18 ++
 include/linux/proportions.h        |   24 +--
 include/linux/proportions_types.h  |   29 ++
 include/linux/rbtree.h             |    8 +-
 include/linux/rbtree_types.h       |   11 +
 include/linux/rcupdate.h           |   11 +-
 include/linux/rcupdate_types.h     |   14 +
 include/linux/sched.h              |  481 +-----------------------------------
 include/linux/sched_types.h        |  493 ++++++++++++++++++++++++++++++++++++
 include/linux/seccomp.h            |    5 +-
 include/linux/seccomp_types.h      |   12 +
 include/linux/sem.h                |    5 +-
 include/linux/sem_types.h          |   10 +
 include/linux/task_io_accounting.h |    2 +
 20 files changed, 633 insertions(+), 559 deletions(-)

index b0ada6f..779afd63 100644
@@ -325,6 +325,7 @@ header-y += sdla.h
 header-y += securebits.h
 header-y += selinux_netlink.h
 header-y += sem.h
+header-y += sem_types.h
 header-y += serial.h
 header-y += serial_core.h
 header-y += serial_reg.h

index 94b48bd..3cc7492 100644
@@ -14,8 +14,8 @@
 #include <linux/spinlock_types.h>
 #include <linux/linkage.h>
 #include <linux/lockdep.h>
-
 #include <asm/atomic.h>
+#include <linux/mutex_types.h>
 
 /*
  * Simple, straightforward mutexes with strict semantics:

@@ -45,22 +45,6 @@
  * - detects multi-task circular deadlocks and prints out all affected
  *   locks and tasks (and only those tasks)
  */
-struct mutex {
-	/* 1: unlocked, 0: locked, negative: locked, possible waiters */
-	atomic_t		count;
-	spinlock_t		wait_lock;
-	struct list_head	wait_list;
-#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP)
-	struct thread_info	*owner;
-#endif
-#ifdef CONFIG_DEBUG_MUTEXES
-	const char 		*name;
-	void			*magic;
-#endif
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-};
 
 /*
  * This is the control structure for tasks blocked on mutex,

new file mode 100644
index 0000000..51113ab
@@ -0,0 +1,22 @@
+#ifndef _LINUX_MUTEX_TYPES_H
+#define _LINUX_MUTEX_TYPES_H
+
+
+struct mutex {
+	/* 1: unlocked, 0: locked, negative: locked, possible waiters */
+	atomic_t		count;
+	spinlock_t		wait_lock;
+	struct list_head	wait_list;
+#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP)
+	struct thread_info	*owner;
+#endif
+#ifdef CONFIG_DEBUG_MUTEXES
+	const char		*name;
+	void			*magic;
+#endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+};
+
+#endif

index dba35e4..ed02421 100644
@@ -92,8 +92,8 @@
 #include <linux/threads.h>
 #include <linux/bitmap.h>
 #include <linux/numa.h>
+#include <linux/nodemask_types.h>
 
-typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
 extern nodemask_t _unused_nodemask_arg_;
 
 #define node_set(node, dst) __node_set((node), &(dst))

new file mode 100644
index 0000000..97b6614
@@ -0,0 +1,11 @@
+#ifndef _LINUX_NODEMASK_TYPES_H
+#define _LINUX_NODEMASK_TYPES_H
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/numa.h>
+
+typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
+
+#endif

index 49f1c2f..8b66f2c 100644
@@ -2,14 +2,7 @@
 #define _LINUX_PID_H
 
 #include <linux/rcupdate.h>
-
-enum pid_type
-{
-	PIDTYPE_PID,
-	PIDTYPE_PGID,
-	PIDTYPE_SID,
-	PIDTYPE_MAX
-};
+#include <linux/pid_types.h>
 
 /*
  * What is struct pid?

@@ -66,12 +59,6 @@ struct pid
 
 extern struct pid init_struct_pid;
 
-struct pid_link
-{
-	struct hlist_node node;
-	struct pid *pid;
-};
-
 static inline struct pid *get_pid(struct pid *pid)
 {
 	if (pid)

new file mode 100644
index 0000000..85ab12a
@@ -0,0 +1,18 @@
+#ifndef _LINUX_PID_TYPES_H
+#define _LINUX_PID_TYPES_H
+
+struct pid;
+
+enum pid_type {
+	PIDTYPE_PID,
+	PIDTYPE_PGID,
+	PIDTYPE_SID,
+	PIDTYPE_MAX
+};
+
+struct pid_link {
+	struct hlist_node node;
+	struct pid *pid;
+};
+
+#endif

index cf793bb..d332304 100644
@@ -12,6 +12,7 @@
 #include <linux/percpu_counter.h>
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
+#include <linux/proportions_types.h>
 
 struct prop_global {
 	/*

@@ -90,29 +91,6 @@ void __prop_inc_percpu_max(struct prop_descriptor *pd,
 			   struct prop_local_percpu *pl, long frac);
 
 
-/*
- * ----- SINGLE ------
- */
-
-struct prop_local_single {
-	/*
-	 * the local events counter
-	 */
-	unsigned long events;
-
-	/*
-	 * snapshot of the last seen global state
-	 * and a lock protecting this state
-	 */
-	unsigned long period;
-	int shift;
-	spinlock_t lock;		/* protect the snapshot state */
-};
-
-#define INIT_PROP_LOCAL_SINGLE(name)			\
-{	.lock = __SPIN_LOCK_UNLOCKED(name.lock),	\
-}
-
 int prop_local_init_single(struct prop_local_single *pl);
 void prop_local_destroy_single(struct prop_local_single *pl);
 void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl);

new file mode 100644
index 0000000..24451fb
@@ -0,0 +1,29 @@
+#ifndef _LINUX_PROPORTIONS_TYPES_H
+#define _LINUX_PROPORTIONS_TYPES_H
+
+/*
+ * ----- SINGLE ------
+ */
+
+#include <linux/spinlock_types.h>
+
+struct prop_local_single {
+	/*
+	 * the local events counter
+	 */
+	unsigned long events;
+
+	/*
+	 * snapshot of the last seen global state
+	 * and a lock protecting this state
+	 */
+	unsigned long period;
+	int shift;
+	spinlock_t lock;		/* protect the snapshot state */
+};
+
+#define INIT_PROP_LOCAL_SINGLE(name)			\
+{	.lock = __SPIN_LOCK_UNLOCKED(name.lock),	\
+}
+
+#endif

index 7066acb..1ca842d 100644
@@ -96,16 +96,10 @@ static inline struct page * rb_insert_page_cache(struct inode * inode,
 
 #include <linux/kernel.h>
 #include <linux/stddef.h>
+#include <linux/rbtree_types.h>
 
-struct rb_node
-{
-	unsigned long  rb_parent_color;
 #define	RB_RED		0
 #define	RB_BLACK	1
-	struct rb_node *rb_right;
-	struct rb_node *rb_left;
-} __attribute__((aligned(sizeof(long))));
-    /* The alignment might seem pointless, but allegedly CRIS needs it */
 
 struct rb_root
 {

new file mode 100644
index 0000000..decfaef
@@ -0,0 +1,11 @@
+#ifndef _LINUX_RBTREE_TYPES_H
+#define _LINUX_RBTREE_TYPES_H
+
+struct rb_node {
+	unsigned long  rb_parent_color;
+	struct rb_node *rb_right;
+	struct rb_node *rb_left;
+} __attribute__((aligned(sizeof(long))));
+    /* The alignment might seem pointless, but allegedly CRIS needs it */
+
+#endif

index af56148..a901ede 100644
@@ -42,6 +42,7 @@
 #include <linux/completion.h>
 #include <linux/debugobjects.h>
 #include <linux/compiler.h>
+#include <linux/rcupdate_types.h>
 
 #ifdef CONFIG_RCU_TORTURE_TEST
 extern int rcutorture_runnable; /* for sysctl */

@@ -52,16 +53,6 @@ extern int rcutorture_runnable; /* for sysctl */
 #define ULONG_CMP_GE(a, b)	(ULONG_MAX / 2 >= (a) - (b))
 #define ULONG_CMP_LT(a, b)	(ULONG_MAX / 2 < (a) - (b))
 
-/**
- * struct rcu_head - callback structure for use with RCU
- * @next: next update requests in a list
- * @func: actual update function to call after the grace period.
- */
-struct rcu_head {
-	struct rcu_head *next;
-	void (*func)(struct rcu_head *head);
-};
-
 /* Exported common interfaces */
 extern void call_rcu_sched(struct rcu_head *head,
 			   void (*func)(struct rcu_head *rcu));

new file mode 100644
index 0000000..5ee7b54
@@ -0,0 +1,14 @@
+#ifndef _LINUX_RCUPDATE_TYPES_H
+#define _LINUX_RCUPDATE_TYPES_H
+
+/**
+ * struct rcu_head - callback structure for use with RCU
+ * @next: next update requests in a list
+ * @func: actual update function to call after the grace period.
+ */
+struct rcu_head {
+	struct rcu_head *next;
+	void (*func)(struct rcu_head *head);
+};
+
+#endif

index 167c333..160860f 100644
@@ -1,14 +1,13 @@
 #ifndef _LINUX_SECCOMP_H
 #define _LINUX_SECCOMP_H
 
+#include <linux/seccomp_types.h>
 
 #ifdef CONFIG_SECCOMP
 
 #include <linux/thread_info.h>
 #include <asm/seccomp.h>
 
-typedef struct { int mode; } seccomp_t;
-
 extern void __secure_computing(int);
 static inline void secure_computing(int this_syscall)
 {

@@ -23,8 +22,6 @@ extern long prctl_set_seccomp(unsigned long);
 
 #include <linux/errno.h>
 
-typedef struct { } seccomp_t;
-
 #define secure_computing(x) do { } while (0)
 
 static inline long prctl_get_seccomp(void)

new file mode 100644
index 0000000..6ccb36f
@@ -0,0 +1,12 @@
+#ifndef _LINUX_SECCOMP_TYPES_H
+#define _LINUX_SECCOMP_TYPES_H
+
+
+#ifdef CONFIG_SECCOMP
+typedef struct { int mode; } seccomp_t;
+#else
+typedef struct { } seccomp_t;
+#endif
+
+#endif
+

index f2961af..e109ed2 100644
@@ -2,6 +2,7 @@
 #define _LINUX_SEM_H
 
 #include <linux/ipc.h>
+#include <linux/sem_types.h>
 
 /* semop flags */
 #define SEM_UNDO        0x1000  /* undo the operation on exit */

@@ -138,10 +139,6 @@ struct sem_undo_list {
 	struct list_head	list_proc;
 };
 
-struct sysv_sem {
-	struct sem_undo_list *undo_list;
-};
-
 #ifdef CONFIG_SYSVIPC
 
 extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);

new file mode 100644
index 0000000..4b938c3
@@ -0,0 +1,10 @@
+#ifndef _LINUX_SEM_TYPES_H
+#define _LINUX_SEM_TYPES_H
+
+struct sem_undo_list;
+
+struct sysv_sem {
+	struct sem_undo_list *undo_list;
+};
+
+#endif

index bdf855c..777cdef 100644
@@ -8,6 +8,8 @@
  * Blame Andrew Morton for all this.
  */
 
+#include <linux/types.h>
+
 struct task_io_accounting {
 #ifdef CONFIG_TASK_XACCT
 	/* bytes read */

Urgh, not pretty.. so why not clean up sched.h properly? There's way too much cruft in there.

It was a proof-of-concept to show that it is doable to have proper definition of task_struct in rcupdate.h. Not an entry for any code beauty contest.

Michal

I like this cleanup, could you continue for this hard job? I will help you if required.

Ingo & Peter - will you accept the patches when it is done.

I certainly like the idea of being able to inline TREE_PREEMPT_RCU's rcu_read_lock() and rcu_read_unlock() using normal C code!

Thanx, Paul

kernel-offset.c can be merged to some branch of your tree for testing inlined TREE_PREEMPT_RCU's rcu_read_lock() and rcu_read_unlock() before the kernel headers splitting is done.

Can the [patch 1/5] be merged to mainline earlier? could you add it to origin/rcu/next?

Thanks,
Lai

Let's first settle on the overall direction, on the off-chance that someone comes up with an approach that doesn't require task_rcu_struct, or that requires it to be located somewhere other than include/linux/rcupdate.h.

Thanx, Paul

And I have created a branch rcu/dev that contains the commits that I don't yet trust enough to send to -next. As before, rcu/kfree_rcu contains the commits that apply kfree_rcu() elsewhere in the kernel.

Thanx, Paul

No, like I said, I think the proposed patch is utterly horrid.

But how about my kernel-offset.c patch? It is clean & simple, it just seems not so normal.

If the proposed splitting patch is horrid, I think we will try to update it as you expect.

If splitting sched.h is wrong, I will try to persuade more people accept the kernel-offset.c patch.

Well, I'm all for cleaning up sched.h, it includes way too much things not strongly related to kernel/sched*.c like a lot of the signal things and the misnamed signal_struct (should be called process_struct or somesuch).

That also causes the inversion between sched.h and wait.h

What I don't like is those _types.h headers, and definitely not the massive explosion of those as per the proposed patch.

Nor do I quite get why all that is needed, sched_types which would define task_struct still needs the new task_rcu_struct bits, and as per the patch you need to split the rcu headers into two. Once you've done that, I don't see why sched.h still needs splitting too.

"struct task_rcu_struct" is just a cleanup patch.

We are trying to use inlined read_read_[un]lock(), it is required that sched.h needs include rcupdate.h which causes many recursive including. Splitting rcupdate.h only does not help.

You're not making any kind of sense there.

linux-2.6# cat kernel/sched_tmp.c

#include <linux/sched.h>

linux-2.6# make kernel/sched_tmp.i
linux-2.6# awk '/^#/ { t=$0 } /rcu_read_lock/ { print t " " $0 }' kernel/sched_tmp.i
# 60 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline void __rcu_read_lock_bh(void)
# 60 "/usr/src/linux-2.6/include/linux/rcupdate.h" extern void __rcu_read_lock(void);
# 258 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline int rcu_read_lock_held(void)
# 258 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline int rcu_read_lock_bh_held(void)
# 258 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline int rcu_read_lock_sched_held(void)
# 559 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline void rcu_read_lock(void)
# 559 "/usr/src/linux-2.6/include/linux/rcupdate.h" __rcu_read_lock();
# 600 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline void rcu_read_lock_bh(void)
# 600 "/usr/src/linux-2.6/include/linux/rcupdate.h" __rcu_read_lock_bh();
# 627 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline void rcu_read_lock_sched(void)
# 627 "/usr/src/linux-2.6/include/linux/rcupdate.h" static inline __attribute__((no_instrument_function)) void rcu_read_lock_sched_notrace(void) # 70 "/usr/src/linux-2.6/include/linux/srcu.h" int __srcu_read_lock(struct srcu_struct *sp) ;
# 103 "/usr/src/linux-2.6/include/linux/srcu.h" static inline int srcu_read_lock_held(struct srcu_struct *sp)
# 149 "/usr/src/linux-2.6/include/linux/srcu.h" static inline int srcu_read_lock(struct srcu_struct *sp)
# 149 "/usr/src/linux-2.6/include/linux/srcu.h" int retval = __srcu_read_lock(sp);
# 1227 "/usr/src/linux-2.6/include/linux/sched.h" int rcu_read_lock_nesting;
# 1786 "/usr/src/linux-2.6/include/linux/sched.h" p->rcu_read_lock_nesting = 0;

There isn't a single rcu_read_lock() user in the include chain of sched.h, therefore its possible to split rcupdate.h such that one part includes the bits needed for sched.h and another part that includes sched.h and provides rcu_read_lock().

Yep, you can easily split struct rcu_head out into its own header file, and then include that into sched.h in place of rcupdate.h without trouble (at least in the few builds I tried).

The trouble comes when you take the next step and include sched.h into include/linux/rcutree.h, which would be needed to allow TREE_PREEMPT_RCU's rcu_read_lock() and rcu_read_unlock() to be inlined. This pulls sched.h into files that it was not already included into, and we do get build failures (the first of which requires changes local to RCU, FWIW).

Of course, it would be good to straighten this out.

Thanx, Paul

And here is a start -- the build is -much- quieter with this patch.

The next layer on this onion is the use of the ctl_table typedef in include/linux/key.h -- which is defined to be struct ctl_table. Anyone know where struct ctl_table is defined? Color me blind, but I am not seeing it...

Thanx, Paul

------------------------------------------------------------------------

new file mode 100644
index 0000000..e0b8add
@@ -0,0 +1,46 @@
+/*
+ * Read-Copy Update mechanism for mutual exclusion: base structures
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2001
+ *
+ * Author: Dipankar Sarma <[email protected]>
+ *
+ * Based on the original work by Paul McKenney <[email protected]>
+ * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
+ * Papers:
+ * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
+ * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
+ *
+ * For detailed explanation of Read-Copy Update mechanism see -
+ *		http://lse.sourceforge.net/locking/rcupdate.html
+ *
+ */
+
+#ifndef __LINUX_RCU_HEAD_H
+#define __LINUX_RCU_HEAD_H
+
+/**
+ * struct rcu_head - callback structure for use with RCU
+ * @next: next update requests in a list
+ * @func: actual update function to call after the grace period.
+ */
+struct rcu_head {
+	struct rcu_head *next;
+	void (*func)(struct rcu_head *head);
+};
+
+#endif /* __LINUX_RCU_HEAD_H */

index ff422d2..ab94fcfb 100644
@@ -52,15 +52,7 @@ extern int rcutorture_runnable; /* for sysctl */
 #define ULONG_CMP_GE(a, b)	(ULONG_MAX / 2 >= (a) - (b))
 #define ULONG_CMP_LT(a, b)	(ULONG_MAX / 2 < (a) - (b))
 
-/**
- * struct rcu_head - callback structure for use with RCU
- * @next: next update requests in a list
- * @func: actual update function to call after the grace period.
- */
-struct rcu_head {
-	struct rcu_head *next;
-	void (*func)(struct rcu_head *head);
-};
+#include <linux/rcu_head.h>
 
 /* Exported common interfaces */
 extern void call_rcu_sched(struct rcu_head *head,

@@ -141,14 +133,6 @@ static inline void rcu_exit_nohz(void)
 
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
-#include <linux/rcutree.h>
-#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
-#include <linux/rcutiny.h>
-#else
-#error "Unknown RCU implementation specified to kernel configuration"
-#endif
-
 /*
  * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
  * initialization and destruction of rcu_head on the stack. rcu_head structures

@@ -797,4 +781,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 }
 #endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
+#include <linux/rcutree.h>
+#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#include <linux/rcutiny.h>
+#else
+#error "Unknown RCU implementation specified to kernel configuration"
+#endif
+
 #endif /* __LINUX_RCUPDATE_H */

index 3a93348..c317eec 100644
@@ -30,6 +30,8 @@
 #ifndef __LINUX_RCUTREE_H
 #define __LINUX_RCUTREE_H
 
+#include <linux/sched.h>
+
 extern void rcu_init(void);
 extern void rcu_note_context_switch(int cpu);
 extern int rcu_needs_cpu(int cpu);

index 83bd2e2..e7c6a90 100644
@@ -78,7 +78,7 @@ struct sched_param {
 #include <linux/topology.h>
 #include <linux/proportions.h>
 #include <linux/seccomp.h>
-#include <linux/rcupdate.h>
+#include <linux/rcu_head.h>
 #include <linux/rculist.h>
 #include <linux/rtmutex.h>
 

@@ -2241,11 +2241,9 @@ int same_thread_group(struct task_struct *p1, struct task_struct *p2)
 	return p1->tgid == p2->tgid;
 }
 
-static inline struct task_struct *next_thread(const struct task_struct *p)
-{
-	return list_entry_rcu(p->thread_group.next,
-			      struct task_struct, thread_group);
-}
+/* Avoid #include hell for inlining rcu_read_lock(). */
+#define next_thread(p) \
+	list_entry_rcu((p)->thread_group.next, struct task_struct, thread_group)
 
 static inline int thread_group_empty(struct task_struct *p)
 {

include/linux/sysctl.h:1015

/* A sysctl table is an array of struct ctl_table: */ struct ctl_table

{
        const char *procname;           /* Text ID for /proc/sys, or zero */
        void *data;
        int maxlen;
        mode_t mode;
        struct ctl_table *child;
        struct ctl_table *parent;       /* Automatically set */
        proc_handler *proc_handler;     /* Callback for text formatting */
        void *extra1;
        void *extra2;
};

Thank you!

Thanx, Paul

And the following patch builds correctly for defconfig x86 builds, while allowing rcupdate.h to see the sched.h definitions as needed to inline rcu_read_lock() and rcu_read_unlock().

I will try allyesconfig builds and see what else breaks.

Thanx, Paul

 include/linux/pid.h      |    2 +-
 include/linux/rcupdate.h |   27 +++++++++------------------
 include/linux/rcutree.h  |    2 ++
 include/linux/sched.h    |   10 ++++------
 include/linux/sem.h      |    2 +-
 include/linux/sysctl.h   |    5 +++--
 include/linux/types.h    |   10 ++++++++++
 kernel/pid_namespace.c   |    2 ++
 8 files changed, 32 insertions(+), 28 deletions(-)

index efceda0..3c5719b 100644
@@ -1,7 +1,7 @@
 #ifndef _LINUX_PID_H
 #define _LINUX_PID_H
 
-#include <linux/rcupdate.h>
+#include <linux/types.h>
 
 enum pid_type
 {

index ff422d2..2fe6402 100644
@@ -33,6 +33,7 @@
 #ifndef __LINUX_RCUPDATE_H
 #define __LINUX_RCUPDATE_H
 
+#include <linux/types.h>
 #include <linux/cache.h>
 #include <linux/spinlock.h>
 #include <linux/threads.h>

@@ -52,16 +53,6 @@ extern int rcutorture_runnable; /* for sysctl */
 #define ULONG_CMP_GE(a, b)	(ULONG_MAX / 2 >= (a) - (b))
 #define ULONG_CMP_LT(a, b)	(ULONG_MAX / 2 < (a) - (b))
 
-/**
- * struct rcu_head - callback structure for use with RCU
- * @next: next update requests in a list
- * @func: actual update function to call after the grace period.
- */
-struct rcu_head {
-	struct rcu_head *next;
-	void (*func)(struct rcu_head *head);
-};
-
 /* Exported common interfaces */
 extern void call_rcu_sched(struct rcu_head *head,
 			   void (*func)(struct rcu_head *rcu));

@@ -141,14 +132,6 @@ static inline void rcu_exit_nohz(void)
 
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
-#include <linux/rcutree.h>
-#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
-#include <linux/rcutiny.h>
-#else
-#error "Unknown RCU implementation specified to kernel configuration"
-#endif
-
 /*
  * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
  * initialization and destruction of rcu_head on the stack. rcu_head structures

@@ -797,4 +780,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 }
 #endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
+#include <linux/rcutree.h>
+#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#include <linux/rcutiny.h>
+#else
+#error "Unknown RCU implementation specified to kernel configuration"
+#endif
+
 #endif /* __LINUX_RCUPDATE_H */

index 3a93348..c317eec 100644
@@ -30,6 +30,8 @@
 #ifndef __LINUX_RCUTREE_H
 #define __LINUX_RCUTREE_H
 
+#include <linux/sched.h>
+
 extern void rcu_init(void);
 extern void rcu_note_context_switch(int cpu);
 extern int rcu_needs_cpu(int cpu);

index 83bd2e2..30a4444 100644
@@ -78,7 +78,7 @@ struct sched_param {
 #include <linux/topology.h>
 #include <linux/proportions.h>
 #include <linux/seccomp.h>
-#include <linux/rcupdate.h>
+#include <linux/types.h>
 #include <linux/rculist.h>
 #include <linux/rtmutex.h>
 

@@ -2241,11 +2241,9 @@ int same_thread_group(struct task_struct *p1, struct task_struct *p2)
 	return p1->tgid == p2->tgid;
 }
 
-static inline struct task_struct *next_thread(const struct task_struct *p)
-{
-	return list_entry_rcu(p->thread_group.next,
-			      struct task_struct, thread_group);
-}
+/* Avoid #include hell for inlining rcu_read_lock(). */
+#define next_thread(p) \
+	list_entry_rcu((p)->thread_group.next, struct task_struct, thread_group)
 
 static inline int thread_group_empty(struct task_struct *p)
 {

index f2961af..8489a1f 100644
@@ -78,7 +78,7 @@ struct  seminfo {
 
 #ifdef __KERNEL__
 #include <asm/atomic.h>
-#include <linux/rcupdate.h>
+#include <linux/types.h>
 #include <linux/cache.h>
 
 struct task_struct;

index 11684d9..be80a59 100644
@@ -19,6 +19,8 @@
  ****************************************************************
  */
 
+#include <linux/key.h>
+
 #ifndef _LINUX_SYSCTL_H
 #define _LINUX_SYSCTL_H
 

@@ -1012,8 +1014,7 @@ extern int proc_do_large_bitmap(struct ctl_table *, int,
  */
 
 /* A sysctl table is an array of struct ctl_table: */
-struct ctl_table 
-{
+struct ctl_table {
 	const char *procname;		/* Text ID for /proc/sys, or zero */
 	void *data;
 	int maxlen;

index 176da8c..868ef8b 100644
@@ -231,6 +231,16 @@ struct hlist_node {
 	struct hlist_node *next, **pprev;
 };
 
+/**
+ * struct rcu_head - callback structure for use with RCU
+ * @next: next update requests in a list
+ * @func: actual update function to call after the grace period.
+ */
+struct rcu_head {
+	struct rcu_head *next;
+	void (*func)(struct rcu_head *head);
+};
+
 struct ustat {
 	__kernel_daddr_t	f_tfree;
 	__kernel_ino_t		f_tinode;

index e9c9adc..bfa75df 100644
@@ -8,6 +8,8 @@
  *
  */
 
+#include <linux/types.h>
+#include <asm/atomic.h>
 #include <linux/pid.h>
 #include <linux/pid_namespace.h>
 #include <linux/syscalls.h>

Looks like an entirely reasonable patch to me ;-)

Quite... a lot better than the original proposal!

-hpa

Glad you both like it!

When I do an allyesconfig build, I do get errors during the "CHECK" phase, when it is putting things into the usr/include in the build tree. I believe that this is because I am exposing different header files to the library-export scripts. The following patch silences some of them, but I am really out of my depth here.

Sam, Jan, Michal, help?

Thanx, Paul

------------------------------------------------------------------------

rcu: cleanups in CHECK portion of kernel build

Silence some complaints about kernel-only functionality being exposed to userspace.

index 00cec4d..a243c13 100644
@@ -648,6 +648,8 @@ struct sysinfo {
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 
+#ifdef __KERNEL__
+
 /**
  * BUILD_BUG_ON - break compile if a condition is true.
  * @condition: the condition which the compiler should know is false.

@@ -673,6 +675,7 @@ extern int __build_bug_on_failed;
 		if (condition) __build_bug_on_failed = 1;	\
 	} while(0)
 #endif
+#endif /* __KERNEL__ */
 
 /* Trap pasters of __FUNCTION__ at compile-time */
 #define __FUNCTION__ (__func__)

index 1904afe..f99c32f 100644
@@ -1064,7 +1064,9 @@ typedef struct mixer_vol_table {
  */
 #define SEQ_DECLAREBUF()		SEQ_USE_EXTBUF()
 
+#ifdef __KERNEL__
 void seqbuf_dump(void);	/* This function must be provided by programs */
+#endif
 
 #define SEQ_PM_DEFINES int __foo_bar___
 

index be80a59..92fb6fa 100644
@@ -19,7 +19,9 @@
  ****************************************************************
  */
 
+#ifdef __KERNEL__
 #include <linux/key.h>
+#endif
 
 #ifndef _LINUX_SYSCTL_H
 #define _LINUX_SYSCTL_H

Easy to split rcupdate.h, hard to resolve the dependence problem.

You can apply the next additional patch when you test:

index 0b4496a..ccbebeb 100644
@@ -788,4 +788,10 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 #error "Unknown RCU implementation specified to kernel configuration"
 #endif
 
+#include <linux/sched.h>
+static inline long test_use_task_struct(void)
+{
+	return current->state;
+}
+
 #endif /* __LINUX_RCUPDATE_H */

I am sure that you are quite correct. ;-)

I am moving _rcu_read_lock() and _rcu_read_unlock() into include/linux/rcutree.h and include/linux/rcutiny.h, and I am sure that more pain will ensue.

One thing I don't understand... How does is it helping to group the task_struct RCU-related fields into a structure? Is that generating better code on your platform due to smaller offsets or something?

Also, does your patchset address the CHECK warnings?

Thanx, Paul

I take it back... I applied the following patch on top of my earlier one, and a defconfig x86 build completed without error. (Though I have not tested the results of the build.)

One possible difference -- I did this work on top of a recent Linus git commit (b2a8b4b81966) rather than on top of my -rcu tree. Also, I have not yet tried an allyesconfig build, which will no doubt locate some more problems.

Thanx, Paul

------------------------------------------------------------------------

rcu: inline preemptible rcu_read_lock() and rcu_read_unlock()

Move the definitions of __rcu_read_lock() and __rcu_read_unlock() from kernel/rcutree_plugin.h to include/linux/rcutree.h and from kernel/rcutiny_plugin.h to include/linux/rcutiny.h, allowing these functions to be inlined.

 include/linux/rcutiny.h |   34 ++++++++++++++++++++++++++++++++++
 include/linux/rcutree.h |   34 ++++++++++++++++++++++++++++++++++
 kernel/rcutiny_plugin.h |   38 ++------------------------------------
 kernel/rcutree_plugin.h |   38 ++------------------------------------
 4 files changed, 72 insertions(+), 72 deletions(-)

rcu: inline preemptible rcu_read_lock() and rcu_read_unlock()

Move the definitions of __rcu_read_lock() and __rcu_read_unlock() from kernel/rcutree_plugin.h to include/linux/rcutree.h and from kernel/rcutiny_plugin.h to include/linux/rcutiny.h, allowing these functions to be inlined.

index 30ebd7c..227a3dd 100644
@@ -47,6 +47,40 @@ static inline void rcu_barrier(void)
 
 void rcu_barrier(void);
 void synchronize_rcu_expedited(void);
+void rcu_read_unlock_special(struct task_struct *t);
+
+/*
+ * Tiny-preemptible RCU implementation for rcu_read_lock().
+ * Just increment ->rcu_read_lock_nesting, shared state will be updated
+ * if we block.
+ */
+static inline void __rcu_read_lock(void)
+{
+	current->rcu_read_lock_nesting++;
+	barrier();
+}
+
+/*
+ * Tiny-preemptible RCU implementation for rcu_read_unlock().
+ * Decrement ->rcu_read_lock_nesting.  If the result is zero (outermost
+ * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
+ * invoke rcu_read_unlock_special() to clean up after a context switch
+ * in an RCU read-side critical section and other special cases.
+ */
+static inline void __rcu_read_unlock(void)
+{
+	struct task_struct *t = current;
+
+	barrier();
+	--t->rcu_read_lock_nesting;
+	barrier();  /* decrement before load of ->rcu_read_unlock_special */
+	if (t->rcu_read_lock_nesting == 0 &&
+	    unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
+		rcu_read_unlock_special(t);
+#ifdef CONFIG_PROVE_LOCKING
+	WARN_ON_ONCE(t->rcu_read_lock_nesting < 0);
+#endif /* #ifdef CONFIG_PROVE_LOCKING */
+}
 
 #endif /* #else #ifdef CONFIG_TINY_RCU */
 

index c317eec..00a2b88 100644
@@ -40,6 +40,40 @@ extern void rcu_cpu_stall_reset(void);
 #ifdef CONFIG_TREE_PREEMPT_RCU
 
 extern void exit_rcu(void);
+extern void rcu_read_unlock_special(struct task_struct *t);
+
+/*
+ * Tree-preemptable RCU implementation for rcu_read_lock().
+ * Just increment ->rcu_read_lock_nesting, shared state will be updated
+ * if we block.
+ */
+static inline void __rcu_read_lock(void)
+{
+	current->rcu_read_lock_nesting++;
+	barrier();
+}
+
+/*
+ * Tree-preemptable RCU implementation for rcu_read_unlock().
+ * Decrement ->rcu_read_lock_nesting.  If the result is zero (outermost
+ * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
+ * invoke rcu_read_unlock_special() to clean up after a context switch
+ * in an RCU read-side critical section and other special cases.
+ */
+static inline void __rcu_read_unlock(void)
+{
+	struct task_struct *t = current;
+
+	barrier();
+	--t->rcu_read_lock_nesting;
+	barrier();  /* decrement before load of ->rcu_read_unlock_special */
+	if (t->rcu_read_lock_nesting == 0 &&
+	    unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
+		rcu_read_unlock_special(t);
+#ifdef CONFIG_PROVE_LOCKING
+	WARN_ON_ONCE(ACCESS_ONCE(t->rcu_read_lock_nesting) < 0);
+#endif /* #ifdef CONFIG_PROVE_LOCKING */
+}
 
 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 

index 3cb8e36..d0e1ac3 100644
@@ -520,23 +520,11 @@ void rcu_preempt_note_context_switch(void)
 }
 
 /*
- * Tiny-preemptible RCU implementation for rcu_read_lock().
- * Just increment ->rcu_read_lock_nesting, shared state will be updated
- * if we block.
- */
-void __rcu_read_lock(void)
-{
-	current->rcu_read_lock_nesting++;
-	barrier();  /* needed if we ever invoke rcu_read_lock in rcutiny.c */
-}
-EXPORT_SYMBOL_GPL(__rcu_read_lock);
-
-/*
  * Handle special cases during rcu_read_unlock(), such as needing to
  * notify RCU core processing or task having blocked during the RCU
  * read-side critical section.
  */
-static void rcu_read_unlock_special(struct task_struct *t)
+void rcu_read_unlock_special(struct task_struct *t)
 {
 	int empty;
 	int empty_exp;

@@ -616,29 +604,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
 #endif /* #ifdef CONFIG_RCU_BOOST */
 	local_irq_restore(flags);
 }
-
-/*
- * Tiny-preemptible RCU implementation for rcu_read_unlock().
- * Decrement ->rcu_read_lock_nesting.  If the result is zero (outermost
- * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
- * invoke rcu_read_unlock_special() to clean up after a context switch
- * in an RCU read-side critical section and other special cases.
- */
-void __rcu_read_unlock(void)
-{
-	struct task_struct *t = current;
-
-	barrier();  /* needed if we ever invoke rcu_read_unlock in rcutiny.c */
-	--t->rcu_read_lock_nesting;
-	barrier();  /* decrement before load of ->rcu_read_unlock_special */
-	if (t->rcu_read_lock_nesting == 0 &&
-	    unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
-		rcu_read_unlock_special(t);
-#ifdef CONFIG_PROVE_LOCKING
-	WARN_ON_ONCE(t->rcu_read_lock_nesting < 0);
-#endif /* #ifdef CONFIG_PROVE_LOCKING */
-}
-EXPORT_SYMBOL_GPL(__rcu_read_unlock);
+EXPORT_SYMBOL_GPL(rcu_read_unlock_special);
 
 /*
  * Check for a quiescent state from the current CPU.  When a task blocks,

index a363871..4b27afd 100644
@@ -196,18 +196,6 @@ static void rcu_preempt_note_context_switch(int cpu)
 }
 
 /*
- * Tree-preemptable RCU implementation for rcu_read_lock().
- * Just increment ->rcu_read_lock_nesting, shared state will be updated
- * if we block.
- */
-void __rcu_read_lock(void)
-{
-	current->rcu_read_lock_nesting++;
-	barrier();  /* needed if we ever invoke rcu_read_lock in rcutree.c */
-}
-EXPORT_SYMBOL_GPL(__rcu_read_lock);
-
-/*
  * Check for preempted RCU readers blocking the current grace period
  * for the specified rcu_node structure.  If the caller needs a reliable
  * answer, it must hold the rcu_node's ->lock.

@@ -261,7 +249,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
  * notify RCU core processing or task having blocked during the RCU
  * read-side critical section.
  */
-static void rcu_read_unlock_special(struct task_struct *t)
+void rcu_read_unlock_special(struct task_struct *t)
 {
 	int empty;
 	int empty_exp;

@@ -332,29 +320,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
 		local_irq_restore(flags);
 	}
 }
-
-/*
- * Tree-preemptable RCU implementation for rcu_read_unlock().
- * Decrement ->rcu_read_lock_nesting.  If the result is zero (outermost
- * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
- * invoke rcu_read_unlock_special() to clean up after a context switch
- * in an RCU read-side critical section and other special cases.
- */
-void __rcu_read_unlock(void)
-{
-	struct task_struct *t = current;
-
-	barrier();  /* needed if we ever invoke rcu_read_unlock in rcutree.c */
-	--t->rcu_read_lock_nesting;
-	barrier();  /* decrement before load of ->rcu_read_unlock_special */
-	if (t->rcu_read_lock_nesting == 0 &&
-	    unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
-		rcu_read_unlock_special(t);
-#ifdef CONFIG_PROVE_LOCKING
-	WARN_ON_ONCE(ACCESS_ONCE(t->rcu_read_lock_nesting) < 0);
-#endif /* #ifdef CONFIG_PROVE_LOCKING */
-}
-EXPORT_SYMBOL_GPL(__rcu_read_unlock);
+EXPORT_SYMBOL_GPL(rcu_read_unlock_special);
 
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 

You don't like task_rcu_struct patch? I think it can make code clearer, and it can also check the code even when CONFIG_PREEMPT_RCU=n.

For rcu_read_[un]lock(), it generates the same code, no better, no worse.

It is just a cleanup patch, it is helpless for making rcu_read_[un]lock() inline, if you don't like it, I will give up it.

when defconfig or allyesconfig, CONFIG_PREEMPT=n and CONFIG_TREE_PREEMPT_RCU=n when you make them "y":

In file included from include/linux/rcupdate.h:764:0,

                 from include/linux/tracepoint.h:19,
                 from include/linux/module.h:18,
                 from include/linux/crypto.h:21,
                 from arch/x86/kernel/asm-offsets.c:8:

include/linux/rcutree.h:50:20: error: static declaration of ‘__rcu_read_lock’ follows non-static declaration include/linux/rcupdate.h:76:13: note: previous declaration of ‘__rcu_read_lock’ was here include/linux/rcutree.h:63:20: error: static declaration of ‘__rcu_read_unlock’ follows non-static declaration include/linux/rcupdate.h:77:13: note: previous declaration of ‘__rcu_read_unlock’ was here make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
make: *** [prepare0] Error 2

I don't know that I feel strongly either way about it. It was necessary with the integer-offset approach, but optional now.

Yep. I need to move the rcu_read_lock() APIs to follow the inclusion of rcutree.h and rcutiny.h. Also add include of sched.h to rcutiny.h. The code movement does bloat the patch a bit. But rcu_assign_pointer() must precede the inclusion of rcutree.h and rcutiny.h, so it is not possible to simply move the inclusions. See below.

Thanx, Paul

------------------------------------------------------------------------

index 00cec4d..a243c13 100644
@@ -648,6 +648,8 @@ struct sysinfo {
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 
+#ifdef __KERNEL__
+
 /**
  * BUILD_BUG_ON - break compile if a condition is true.
  * @condition: the condition which the compiler should know is false.