s390/runtime instrumentation: simplify task exit handling

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>

diff --git a/arch/s390/include/asm/runtime_instr.h b/arch/s390/include/asm/runtime_instr.h
index ea8896b..2502d05 100644 (file)
--- 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 runtime_instr_cb *cb_next,
                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 */

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 203b7cd..7d4c550 100644 (file)
--- 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 *dead_task)
 
 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)

diff --git a/arch/s390/kernel/runtime_instr.c b/arch/s390/kernel/runtime_instr.c
index d85c648..94c9ba7 100644 (file)
--- 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 runtime_instr_cb *cb)
        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, command)
                return -EOPNOTSUPP;
 
        if (command == S390_RUNTIME_INSTR_STOP) {
-               exit_thread_runtime_instr();
+               disable_runtime_instr();
                return 0;
        }