From: Sébastien Dugué <sebastien.dugue@bull.net>

Move good_sigevent() from posix-timers.c to signal.c where it belongs, clean
it up, rename it to sigevent_find_task() to better describe what the function
does and make it non-static so that it can be used by other subsystems.

Signed-off-by: Sébastien Dugué <sebastien.dugue@bull.net>
Cc: Bharata B Rao <bharata@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Suparna Bhattacharya <suparna@in.ibm.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Benjamin LaHaise <bcrl@linux.intel.com>
Cc: Jean Pierre Dion <jean-pierre.dion@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/signal.h |    1 +
 kernel/posix-timers.c  |   19 +------------------
 kernel/signal.c        |   24 ++++++++++++++++++++++++
 3 files changed, 26 insertions(+), 18 deletions(-)

diff -puN include/linux/signal.h~make-good_sigevent-non-static include/linux/signal.h
--- a/include/linux/signal.h~make-good_sigevent-non-static
+++ a/include/linux/signal.h
@@ -240,6 +240,7 @@ extern int sigprocmask(int, sigset_t *, 
 
 struct pt_regs;
 extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
+extern struct task_struct * sigevent_find_task(sigevent_t *);
 
 extern struct kmem_cache *sighand_cachep;
 
diff -puN kernel/posix-timers.c~make-good_sigevent-non-static kernel/posix-timers.c
--- a/kernel/posix-timers.c~make-good_sigevent-non-static
+++ a/kernel/posix-timers.c
@@ -367,23 +367,6 @@ static enum hrtimer_restart posix_timer_
 	return ret;
 }
 
-static struct task_struct * good_sigevent(sigevent_t * event)
-{
-	struct task_struct *rtn = current->group_leader;
-
-	if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
-		(!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
-		 rtn->tgid != current->tgid ||
-		 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
-		return NULL;
-
-	if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
-	    ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
-		return NULL;
-
-	return rtn;
-}
-
 void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock)
 {
 	if ((unsigned) clock_id >= MAX_CLOCKS) {
@@ -496,7 +479,7 @@ sys_timer_create(const clockid_t which_c
 		new_timer->it_sigev_value = event.sigev_value;
 
 		read_lock(&tasklist_lock);
-		if ((process = good_sigevent(&event))) {
+		if ((process = sigevent_find_task(&event))) {
 			/*
 			 * We may be setting up this process for another
 			 * thread.  It may be exiting.  To catch this
diff -puN kernel/signal.c~make-good_sigevent-non-static kernel/signal.c
--- a/kernel/signal.c~make-good_sigevent-non-static
+++ a/kernel/signal.c
@@ -1089,6 +1089,30 @@ int group_send_sig_info(int sig, struct 
 	return ret;
 }
 
+/***
+ * sigevent_find_task - check and get target task from a sigevent.
+ * @event: the sigevent to be checked
+ *
+ * This function must be called with the tasklist_lock held for reading.
+ */
+struct task_struct * sigevent_find_task(sigevent_t * event)
+{
+	struct task_struct *task = NULL;
+
+	if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
+		return NULL;
+
+	if ((event->sigev_notify & SIGEV_THREAD_ID ) == SIGEV_THREAD_ID) {
+		task = find_task_by_pid(event->sigev_notify_thread_id);
+
+		if (!task || task->tgid != current->tgid)
+			task = NULL;
+	} else if (event->sigev_notify == SIGEV_SIGNAL)
+		task = current->group_leader;
+
+	return task;
+}
+
 /*
  * kill_pgrp_info() sends a signal to a process group: this is what the tty
  * control characters do (^C, ^Z etc)
_