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%3Ba=su...

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 stable@vger.kernel.org know about it.

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

From: Heiko Carstens heiko.carstens@de.ibm.com Date: Mon, 11 Sep 2017 11:24:22 +0200 Subject: s390/runtime instrumentation: simplify task exit handling

From: Heiko Carstens heiko.carstens@de.ibm.com

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 heiko.carstens@de.ibm.com Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- 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(-)

--- a/arch/s390/include/asm/runtime_instr.h +++ b/arch/s390/include/asm/runtime_instr.h @@ -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 */ --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -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) --- a/arch/s390/kernel/runtime_instr.c +++ b/arch/s390/kernel/runtime_instr.c @@ -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 heiko.carstens@de.ibm.com are

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