[PATCH] tracehooks: remove death_cookie from exit_notify() path

[Oleg Nesterov]

On 07/28, Roland McGrath wrote:
>
> > OK, I'll send the first patch upstream, then I re-send 2-4 with updated
> > comments to you.
>
> Ok, good.  When I get those I'll merge those upstream-bound ones into the
> tracehook git branch (now just signals-tracehook_notify_jctl-change.patch)
> and merge the utrace changes into the utrace branch.

Since we are going to send some tracehook changes upstream, how about the
patch below as well?

I think it is very unlikely we will need death_cookie in the near future,
and it is always nice to simplify the code.

Oleg.

--------------------------------------------------------------------------
[PATCH] tracehooks: remove death_cookie from exit_notify() path

Remove "void *death_cookie" from exit_notify() pathes, it is not really
used.


--- __UTRACE/include/linux/utrace.h~KILL_COOKIE	2009-07-28 23:27:14.000000000 +0200
+++ __UTRACE/include/linux/utrace.h	2009-07-29 02:05:07.000000000 +0200
@@ -105,7 +105,7 @@ void utrace_finish_vfork(struct task_str
 	__attribute__((weak));
 void utrace_report_exit(long *exit_code)
 	__attribute__((weak));
-void utrace_report_death(struct task_struct *, struct utrace *, bool, int)
+void utrace_report_death(struct task_struct *, bool, int)
 	__attribute__((weak));
 void utrace_report_jctl(int notify, int type)
 	__attribute__((weak));
--- __UTRACE/include/linux/tracehook.h~KILL_COOKIE	2009-07-28 23:28:47.000000000 +0200
+++ __UTRACE/include/linux/tracehook.h	2009-07-29 02:04:42.000000000 +0200
@@ -538,7 +538,6 @@ static inline void tracehook_finish_jctl
 /**
  * tracehook_notify_death - task is dead, ready to notify parent
  * @task:		@current task now exiting
- * @death_cookie:	value to pass to tracehook_report_death()
  * @group_dead:		nonzero if this was the last thread in the group to die
  *
  * A return value >= 0 means call do_notify_parent() with that signal
@@ -550,10 +549,8 @@ static inline void tracehook_finish_jctl
  * Called with write_lock_irq(&tasklist_lock) held.
  */
 static inline int tracehook_notify_death(struct task_struct *task,
-					 void **death_cookie, int group_dead)
+						int group_dead)
 {
-	*death_cookie = task_utrace_struct(task);
-
 	if (task_detached(task))
 		return task->ptrace ? SIGCHLD : DEATH_REAP;
 
@@ -572,14 +569,12 @@ static inline int tracehook_notify_death
  * tracehook_report_death - task is dead and ready to be reaped
  * @task:		@current task now exiting
  * @signal:		return value from tracheook_notify_death()
- * @death_cookie:	value passed back from tracehook_notify_death()
  * @group_dead:		nonzero if this was the last thread in the group to die
  *
  * Thread has just become a zombie or is about to self-reap.  If positive,
  * @signal is the signal number just sent to the parent (usually %SIGCHLD).
  * If @signal is %DEATH_REAP, this thread will self-reap.  If @signal is
  * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie.
- * The @death_cookie was passed back by tracehook_notify_death().
  *
  * If normal reaping is not inhibited, @task->exit_state might be changing
  * in parallel.
@@ -587,8 +582,7 @@ static inline int tracehook_notify_death
  * Called without locks.
  */
 static inline void tracehook_report_death(struct task_struct *task,
-					  int signal, void *death_cookie,
-					  int group_dead)
+					  int signal, int group_dead)
 {
 	/*
 	 * This barrier ensures that our caller's setting of
@@ -603,7 +597,7 @@ static inline void tracehook_report_deat
 	 */
 	smp_mb();
 	if (task_utrace_flags(task) & _UTRACE_DEATH_EVENTS)
-		utrace_report_death(task, death_cookie, group_dead, signal);
+		utrace_report_death(task, group_dead, signal);
 }
 
 #ifdef TIF_NOTIFY_RESUME
--- __UTRACE/kernel/exit.c~KILL_COOKIE	2009-07-13 17:44:27.000000000 +0200
+++ __UTRACE/kernel/exit.c	2009-07-29 02:02:47.000000000 +0200
@@ -803,7 +803,6 @@ static void forget_original_parent(struc
 static void exit_notify(struct task_struct *tsk, int group_dead)
 {
 	int signal;
-	void *cookie;
 
 	/*
 	 * This does two things:
@@ -839,7 +838,7 @@ static void exit_notify(struct task_stru
 	     tsk->self_exec_id != tsk->parent_exec_id))
 		tsk->exit_signal = SIGCHLD;
 
-	signal = tracehook_notify_death(tsk, &cookie, group_dead);
+	signal = tracehook_notify_death(tsk, group_dead);
 	if (signal >= 0)
 		signal = do_notify_parent(tsk, signal);
 
@@ -853,7 +852,7 @@ static void exit_notify(struct task_stru
 
 	write_unlock_irq(&tasklist_lock);
 
-	tracehook_report_death(tsk, signal, cookie, group_dead);
+	tracehook_report_death(tsk, signal, group_dead);
 
 	/* If the process is dead, release it - nobody will wait for it */
 	if (signal == DEATH_REAP)
--- __UTRACE/kernel/utrace.c~KILL_COOKIE	2009-07-29 00:14:42.000000000 +0200
+++ __UTRACE/kernel/utrace.c	2009-07-29 02:06:20.000000000 +0200
@@ -1659,9 +1659,9 @@ void utrace_report_exit(long *exit_code)
  * For this reason, utrace_release_task checks for the event bits that get
  * us here, and delays its cleanup for us to do.
  */
-void utrace_report_death(struct task_struct *task, struct utrace *utrace,
-			 bool group_dead, int signal)
+void utrace_report_death(struct task_struct *task, bool group_dead, int signal)
 {
+	struct utrace *utrace = task_utrace_struct(task);
 	INIT_REPORT(report);
 
 	BUG_ON(!task->exit_state);