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Patch "s390/runtime instrumentation: simplify task exit handling" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Dec 6, 2017

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This is a note to let you know that I've just added the patch titled

s390/runtime instrumentation: simplify task exit handling

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
s390-runtime-instrumentation-simplify-task-exit-handling.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 8d9047f8b967ce6181fd824ae922978e1b055cc0 Mon Sep 17 00:00:00 2001

From: Heiko Carstens <[email protected]>
Date: Mon, 11 Sep 2017 11:24:22 +0200
Subject: s390/runtime instrumentation: simplify task exit handling

From: Heiko Carstens <[email protected]>

commit 8d9047f8b967ce6181fd824ae922978e1b055cc0 upstream.

Free data structures required for runtime instrumentation from arch_release_task_struct(). This allows to simplify the code a bit, and also makes the semantics a bit easier: arch_release_task_struct() is never called from the task that is being removed.

In addition this allows to get rid of exit_thread() in a later patch.

Signed-off-by Heiko Carstens <[email protected]>
Signed-off-by Martin Schwidefsky <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/s390/include/asm/runtime_instr.h |    4 +++-
 arch/s390/kernel/process.c            |    3 +--
 arch/s390/kernel/runtime_instr.c      |   30 +++++++++++++++---------------
 3 files changed, 19 insertions(+), 18 deletions(-)
arch/s390/include/asm/runtime_instr.h +3 -1
@@ -85,6 +85,8 @@ static inline void restore_ri_cb(struct
 		load_runtime_instr_cb(&runtime_instr_empty_cb);
 }
 
-void exit_thread_runtime_instr(void);
+struct task_struct;
+
+void runtime_instr_release(struct task_struct *tsk);
 
 #endif /* _RUNTIME_INSTR_H */
arch/s390/kernel/process.c +1 -2
@@ -70,8 +70,6 @@ extern void kernel_thread_starter(void);
  */
 void exit_thread(struct task_struct *tsk)
 {
-	if (tsk == current)
-		exit_thread_runtime_instr();
 }
 
 void flush_thread(void)

@@ -84,6 +82,7 @@ void release_thread(struct task_struct *
 
 void arch_release_task_struct(struct task_struct *tsk)
 {
+	runtime_instr_release(tsk);
 }
 
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
arch/s390/kernel/runtime_instr.c +15 -15
@@ -18,11 +18,24 @@
 /* empty control block to disable RI by loading it */
 struct runtime_instr_cb runtime_instr_empty_cb;
 
+void runtime_instr_release(struct task_struct *tsk)
+{
+	kfree(tsk->thread.ri_cb);
+}
+
 static void disable_runtime_instr(void)
 {
-	struct pt_regs *regs = task_pt_regs(current);
+	struct task_struct *task = current;
+	struct pt_regs *regs;
 
+	if (!task->thread.ri_cb)
+		return;
+	regs = task_pt_regs(task);
+	preempt_disable();
 	load_runtime_instr_cb(&runtime_instr_empty_cb);
+	kfree(task->thread.ri_cb);
+	task->thread.ri_cb = NULL;
+	preempt_enable();
 
 	/*
 	 * Make sure the RI bit is deleted from the PSW. If the user did not

@@ -43,19 +56,6 @@ static void init_runtime_instr_cb(struct
 	cb->valid = 1;
 }
 
-void exit_thread_runtime_instr(void)
-{
-	struct task_struct *task = current;
-
-	preempt_disable();
-	if (!task->thread.ri_cb)
-		return;
-	disable_runtime_instr();
-	kfree(task->thread.ri_cb);
-	task->thread.ri_cb = NULL;
-	preempt_enable();
-}
-
 SYSCALL_DEFINE1(s390_runtime_instr, int, command)
 {
 	struct runtime_instr_cb *cb;

@@ -64,7 +64,7 @@ SYSCALL_DEFINE1(s390_runtime_instr, int,
 		return -EOPNOTSUPP;
 
 	if (command == S390_RUNTIME_INSTR_STOP) {
-		exit_thread_runtime_instr();
+		disable_runtime_instr();
 		return 0;
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/s390-runtime-instrumentation-simplify-task-exit-handling.patch