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debugobjects: print more data

PATCH In review Stanislaw Gruszka 2 participants 6 messages Mar 7, 2011 – Mar 8, 2011

Subsystems (3)
Library code Workqueue Debugobjects:
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Stanislaw Gruszka

author
#0 lore raw

PATCH v5 1/1 debugobjects: print more data

On complex subsystems like mac80211, structures may include many timers and works. In such case, based only on call trace and object type is hard to conclude where bug could possibly be.

Patch extend debug object descriptor to additional debug hint function. If defined, it return address, which have associated kernel symbol (i.e. hrtimer->function pointer). We print that symbol when bug is detected, to identify the object.

Patch contains debug hint methods for timer_list, work_struct and hrtimer.

Signed-off-by Stanislaw Gruszka <[email protected]>

---
Cc Andrew, perhaps this could be merged through mm?

v1 -> v2:
- do not invent custom functions for print symbols
- remove not necessary null check, use same call convention like other methods
- fix stray whitespace
- print only symbol name (no function pointer)
v2 -> v3:
- remove remaining kallsyms changes
v3 -> v4:
- make callbacks static
v4 -> v5:
- do not drop WARN
- change "print" method to "debug_hint"

 include/linux/debugobjects.h |    5 ++++-
 kernel/hrtimer.c             |    6 ++++++
 kernel/timer.c               |    6 ++++++
 kernel/workqueue.c           |    6 ++++++
 lib/debugobjects.c           |    9 ++++++---
 5 files changed, 28 insertions(+), 4 deletions(-)
include/linux/debugobjects.h +4 -1
index 597692f..5580c4e 100644
@@ -34,7 +34,10 @@ struct debug_obj {
 
 /**
  * struct debug_obj_descr - object type specific debug description structure
+ *
  * @name:		name of the object typee
+ * @debug_hint:		function returning address, which have associated
+ *			kernel symbol, to allow identify the object
  * @fixup_init:		fixup function, which is called when the init check
  *			fails
  * @fixup_activate:	fixup function, which is called when the activate check

@@ -46,7 +49,7 @@ struct debug_obj {
  */
 struct debug_obj_descr {
 	const char		*name;
-
+	void *(*debug_hint)	(void *addr);
 	int (*fixup_init)	(void *addr, enum debug_obj_state state);
 	int (*fixup_activate)	(void *addr, enum debug_obj_state state);
 	int (*fixup_destroy)	(void *addr, enum debug_obj_state state);
kernel/hrtimer.c +6 -0
index 0c8d7c0..e38f5a0 100644
@@ -334,6 +334,11 @@ EXPORT_SYMBOL_GPL(ktime_add_safe);
 
 static struct debug_obj_descr hrtimer_debug_descr;
 
+static void *hrtimer_debug_hint(void *addr)
+{
+	return ((struct hrtimer *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -393,6 +398,7 @@ static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr hrtimer_debug_descr = {
 	.name		= "hrtimer",
+	.debug_hint	= hrtimer_debug_hint,
 	.fixup_init	= hrtimer_fixup_init,
 	.fixup_activate	= hrtimer_fixup_activate,
 	.fixup_free	= hrtimer_fixup_free,
kernel/timer.c +6 -0
index d645992..33a6792 100644
@@ -404,6 +404,11 @@ static void timer_stats_account_timer(struct timer_list *timer) {}
 
 static struct debug_obj_descr timer_debug_descr;
 
+static void *timer_debug_hint(void *addr)
+{
+	return ((struct timer_list *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -477,6 +482,7 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr timer_debug_descr = {
 	.name		= "timer_list",
+	.debug_hint	= timer_debug_hint,
 	.fixup_init	= timer_fixup_init,
 	.fixup_activate	= timer_fixup_activate,
 	.fixup_free	= timer_fixup_free,
kernel/workqueue.c +6 -0
index 11869fa..5f7c49f 100644
@@ -314,6 +314,11 @@ static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
 
 static struct debug_obj_descr work_debug_descr;
 
+static void *work_debug_hint(void *addr)
+{
+	return ((struct work_struct *work) addr)->func;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -385,6 +390,7 @@ static int work_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr work_debug_descr = {
 	.name		= "work_struct",
+	.debug_hint	= work_debug_hint,
 	.fixup_init	= work_fixup_init,
 	.fixup_activate	= work_fixup_activate,
 	.fixup_free	= work_fixup_free,
lib/debugobjects.c +6 -3
index deebcc5..9d86e45 100644
@@ -249,14 +249,17 @@ static struct debug_bucket *get_bucket(unsigned long addr)
 
 static void debug_print_object(struct debug_obj *obj, char *msg)
 {
+	struct debug_obj_descr *descr = obj->descr;
 	static int limit;
 
-	if (limit < 5 && obj->descr != descr_test) {
+	if (limit < 5 && descr != descr_test) {
+		void *hint = descr->debug_hint ?
+			descr->debug_hint(obj->object) : NULL;
 		limit++;
 		WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
-				 "object type: %s\n",
+				 "object type: %s hint: %pS\n",
 			msg, obj_states[obj->state], obj->astate,
-			obj->descr->name);
+			descr->name, hint);
 	}
 	debug_objects_warnings++;
 }
Signature · 1 line
1.7.1
#1 lore raw
Quoted 9 lines · Stanislaw Gruszka

On complex subsystems like mac80211, structures may include many timers and works. In such case, based only on call trace and object type is hard to conclude where bug could possibly be.

Patch extend debug object descriptor to additional debug hint function. If defined, it return address, which have associated kernel symbol (i.e. hrtimer->function pointer). We print that symbol when bug is detected, to identify the object.

Quoted 6 lines

Patch contains debug hint methods for timer_list, work_struct and hrtimer.

Signed-off-by Stanislaw Gruszka <[email protected]>

---
Cc Andrew, perhaps this could be merged through mm?

It's on my list. I just was away for a few days.

author
#2 lore raw

[tip:core/debugobjects] debugobjects: Add hint for better object identification

In reply to Stanislaw Gruszka
Commit-ID:  be1e60006500eebfb3b82e0c0915ea898dfd224e
Gitweb:     http://git.kernel.org/tip/be1e60006500eebfb3b82e0c0915ea898dfd224e
Author:     Stanislaw Gruszka <[email protected]>
AuthorDate: Mon, 7 Mar 2011 09:58:33 +0100
Committer:  Thomas Gleixner <[email protected]>
CommitDate: Tue, 8 Mar 2011 10:25:47 +0100

debugobjects: Add hint for better object identification

In complex subsystems like mac80211 structures can contain several timers and work structs, so identifying a specific instance from the call trace and object type output of debugobjects can be hard.

Allow the subsystems which support debugobjects to provide a hint function. This function returns a pointer to a kernel address (preferrably the objects callback function) which is printed along with the debugobjects type.

Add hint methods for timer_list, work_struct and hrtimer.

[ tglx: Massaged changelog ]

Signed-off-by Stanislaw Gruszka <[email protected]>

LKML-Reference: <[email protected]>

Signed-off-by Thomas Gleixner <[email protected]>
---
 include/linux/debugobjects.h |    5 ++++-
 kernel/hrtimer.c             |    6 ++++++
 kernel/timer.c               |    6 ++++++
 kernel/workqueue.c           |    6 ++++++
 lib/debugobjects.c           |    9 ++++++---
 5 files changed, 28 insertions(+), 4 deletions(-)
include/linux/debugobjects.h +4 -1
index 597692f..65970b8 100644
@@ -34,7 +34,10 @@ struct debug_obj {
 
 /**
  * struct debug_obj_descr - object type specific debug description structure
+ *
  * @name:		name of the object typee
+ * @debug_hint:		function returning address, which have associated
+ *			kernel symbol, to allow identify the object
  * @fixup_init:		fixup function, which is called when the init check
  *			fails
  * @fixup_activate:	fixup function, which is called when the activate check

@@ -46,7 +49,7 @@ struct debug_obj {
  */
 struct debug_obj_descr {
 	const char		*name;
-
+	void *(*debug_hint)	(void *addr);
 	int (*fixup_init)	(void *addr, enum debug_obj_state state);
 	int (*fixup_activate)	(void *addr, enum debug_obj_state state);
 	int (*fixup_destroy)	(void *addr, enum debug_obj_state state);
kernel/hrtimer.c +6 -0
index 0c8d7c0..e38f5a0 100644
@@ -334,6 +334,11 @@ EXPORT_SYMBOL_GPL(ktime_add_safe);
 
 static struct debug_obj_descr hrtimer_debug_descr;
 
+static void *hrtimer_debug_hint(void *addr)
+{
+	return ((struct hrtimer *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -393,6 +398,7 @@ static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr hrtimer_debug_descr = {
 	.name		= "hrtimer",
+	.debug_hint	= hrtimer_debug_hint,
 	.fixup_init	= hrtimer_fixup_init,
 	.fixup_activate	= hrtimer_fixup_activate,
 	.fixup_free	= hrtimer_fixup_free,
kernel/timer.c +6 -0
index d645992..33a6792 100644
@@ -404,6 +404,11 @@ static void timer_stats_account_timer(struct timer_list *timer) {}
 
 static struct debug_obj_descr timer_debug_descr;
 
+static void *timer_debug_hint(void *addr)
+{
+	return ((struct timer_list *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -477,6 +482,7 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr timer_debug_descr = {
 	.name		= "timer_list",
+	.debug_hint	= timer_debug_hint,
 	.fixup_init	= timer_fixup_init,
 	.fixup_activate	= timer_fixup_activate,
 	.fixup_free	= timer_fixup_free,
kernel/workqueue.c +6 -0
index ee6578b..5baa45c 100644
@@ -316,6 +316,11 @@ static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
 
 static struct debug_obj_descr work_debug_descr;
 
+static void *work_debug_hint(void *addr)
+{
+	return ((struct work_struct *work) addr)->func;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -387,6 +392,7 @@ static int work_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr work_debug_descr = {
 	.name		= "work_struct",
+	.debug_hint	= work_debug_hint,
 	.fixup_init	= work_fixup_init,
 	.fixup_activate	= work_fixup_activate,
 	.fixup_free	= work_fixup_free,
lib/debugobjects.c +6 -3
index deebcc5..9d86e45 100644
@@ -249,14 +249,17 @@ static struct debug_bucket *get_bucket(unsigned long addr)
 
 static void debug_print_object(struct debug_obj *obj, char *msg)
 {
+	struct debug_obj_descr *descr = obj->descr;
 	static int limit;
 
-	if (limit < 5 && obj->descr != descr_test) {
+	if (limit < 5 && descr != descr_test) {
+		void *hint = descr->debug_hint ?
+			descr->debug_hint(obj->object) : NULL;
 		limit++;
 		WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
-				 "object type: %s\n",
+				 "object type: %s hint: %pS\n",
 			msg, obj_states[obj->state], obj->astate,
-			obj->descr->name);
+			descr->name, hint);
 	}
 	debug_objects_warnings++;
 }
#3 lore raw

Re: [tip:core/debugobjects] debugobjects: Add hint for better object identification

kernel/workqueue.c static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, · line 322

Quoted 5 lines · tip-bot for Stanislaw Gruszka
kernel/workqueue.c +4 -0
+static void *work_debug_hint(void *addr)
+{
+	return ((struct work_struct *work) addr)->func;
+}

Care to send compilable patches ?

Thanks,

tglx

author
#4 lore raw

Re: [tip:core/debugobjects] debugobjects: Add hint for better object identification

Quoted 5 lines · Thomas Gleixner

kernel/workqueue.c static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, · line 321

Quoted 4 lines · tip-bot for Stanislaw Gruszka
kernel/workqueue.c +3 -0
+static void *work_debug_hint(void *addr)
+{
+	return ((struct work_struct *work) addr)->func;

Uhh.

Quoted 1 line

Care to send compilable patches ?

I'm sorry, it compile here with
gcc version 4.4.4 20100726 (Red Hat 4.4.4-13).

Could you fix it, or should I repost?

Stanislaw

author
#5 lore raw

[tip:core/debugobjects] debugobjects: Add hint for better object identification

In reply to Stanislaw Gruszka
Commit-ID:  997772884036e6e121de39322179989154437d9f
Gitweb:     http://git.kernel.org/tip/997772884036e6e121de39322179989154437d9f
Author:     Stanislaw Gruszka <[email protected]>
AuthorDate: Mon, 7 Mar 2011 09:58:33 +0100
Committer:  Thomas Gleixner <[email protected]>
CommitDate: Tue, 8 Mar 2011 16:10:38 +0100

debugobjects: Add hint for better object identification

In complex subsystems like mac80211 structures can contain several timers and work structs, so identifying a specific instance from the call trace and object type output of debugobjects can be hard.

Allow the subsystems which support debugobjects to provide a hint function. This function returns a pointer to a kernel address (preferrably the objects callback function) which is printed along with the debugobjects type.

Add hint methods for timer_list, work_struct and hrtimer.

[ tglx: Massaged changelog, made it compile ]

Signed-off-by Stanislaw Gruszka <[email protected]>

LKML-Reference: <[email protected]>

Signed-off-by Thomas Gleixner <[email protected]>
---
 include/linux/debugobjects.h |    5 ++++-
 kernel/hrtimer.c             |    6 ++++++
 kernel/timer.c               |    6 ++++++
 kernel/workqueue.c           |    6 ++++++
 lib/debugobjects.c           |    9 ++++++---
 5 files changed, 28 insertions(+), 4 deletions(-)
include/linux/debugobjects.h +4 -1
index 597692f..65970b8 100644
@@ -34,7 +34,10 @@ struct debug_obj {
 
 /**
  * struct debug_obj_descr - object type specific debug description structure
+ *
  * @name:		name of the object typee
+ * @debug_hint:		function returning address, which have associated
+ *			kernel symbol, to allow identify the object
  * @fixup_init:		fixup function, which is called when the init check
  *			fails
  * @fixup_activate:	fixup function, which is called when the activate check

@@ -46,7 +49,7 @@ struct debug_obj {
  */
 struct debug_obj_descr {
 	const char		*name;
-
+	void *(*debug_hint)	(void *addr);
 	int (*fixup_init)	(void *addr, enum debug_obj_state state);
 	int (*fixup_activate)	(void *addr, enum debug_obj_state state);
 	int (*fixup_destroy)	(void *addr, enum debug_obj_state state);
kernel/hrtimer.c +6 -0
index 0c8d7c0..e38f5a0 100644
@@ -334,6 +334,11 @@ EXPORT_SYMBOL_GPL(ktime_add_safe);
 
 static struct debug_obj_descr hrtimer_debug_descr;
 
+static void *hrtimer_debug_hint(void *addr)
+{
+	return ((struct hrtimer *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -393,6 +398,7 @@ static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr hrtimer_debug_descr = {
 	.name		= "hrtimer",
+	.debug_hint	= hrtimer_debug_hint,
 	.fixup_init	= hrtimer_fixup_init,
 	.fixup_activate	= hrtimer_fixup_activate,
 	.fixup_free	= hrtimer_fixup_free,
kernel/timer.c +6 -0
index d645992..33a6792 100644
@@ -404,6 +404,11 @@ static void timer_stats_account_timer(struct timer_list *timer) {}
 
 static struct debug_obj_descr timer_debug_descr;
 
+static void *timer_debug_hint(void *addr)
+{
+	return ((struct timer_list *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -477,6 +482,7 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr timer_debug_descr = {
 	.name		= "timer_list",
+	.debug_hint	= timer_debug_hint,
 	.fixup_init	= timer_fixup_init,
 	.fixup_activate	= timer_fixup_activate,
 	.fixup_free	= timer_fixup_free,
kernel/workqueue.c +6 -0
index ee6578b..b5fe4c0 100644
@@ -316,6 +316,11 @@ static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
 
 static struct debug_obj_descr work_debug_descr;
 
+static void *work_debug_hint(void *addr)
+{
+	return ((struct work_struct *) addr)->func;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized

@@ -387,6 +392,7 @@ static int work_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr work_debug_descr = {
 	.name		= "work_struct",
+	.debug_hint	= work_debug_hint,
 	.fixup_init	= work_fixup_init,
 	.fixup_activate	= work_fixup_activate,
 	.fixup_free	= work_fixup_free,
lib/debugobjects.c +6 -3
index deebcc5..9d86e45 100644
@@ -249,14 +249,17 @@ static struct debug_bucket *get_bucket(unsigned long addr)
 
 static void debug_print_object(struct debug_obj *obj, char *msg)
 {
+	struct debug_obj_descr *descr = obj->descr;
 	static int limit;
 
-	if (limit < 5 && obj->descr != descr_test) {
+	if (limit < 5 && descr != descr_test) {
+		void *hint = descr->debug_hint ?
+			descr->debug_hint(obj->object) : NULL;
 		limit++;
 		WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
-				 "object type: %s\n",
+				 "object type: %s hint: %pS\n",
 			msg, obj_states[obj->state], obj->astate,
-			obj->descr->name);
+			descr->name, hint);
 	}
 	debug_objects_warnings++;
 }