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Subject[PATCH 4.14 04/75] s390/runtime instrumentation: simplify task exit handling
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

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>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/include/asm/runtime_instr.h | 4 +++-
arch/s390/kernel/process.c | 5 ++---
arch/s390/kernel/runtime_instr.c | 30 +++++++++++++++---------------
3 files changed, 20 insertions(+), 19 deletions(-)

--- a/arch/s390/include/asm/runtime_instr.h
+++ b/arch/s390/include/asm/runtime_instr.h
@@ -86,6 +86,8 @@ 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
@@ -49,10 +49,8 @@ extern void kernel_thread_starter(void);
*/
void exit_thread(struct task_struct *tsk)
{
- if (tsk == current) {
- exit_thread_runtime_instr();
+ if (tsk == current)
exit_thread_gs();
- }
}

void flush_thread(void)
@@ -65,6 +63,7 @@ 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
@@ -21,11 +21,24 @@
/* 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
@@ -46,19 +59,6 @@ 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;
@@ -67,7 +67,7 @@ SYSCALL_DEFINE1(s390_runtime_instr, int,
return -EOPNOTSUPP;

if (command == S390_RUNTIME_INSTR_STOP) {
- exit_thread_runtime_instr();
+ disable_runtime_instr();
return 0;
}


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