From: Eric W. Biederman <ebiederm@xmission.com>
Date: Sat, 21 Jul 2018 05:00:29 +0000 (-0500)
Subject: posix-timers: Noralize good_sigevent
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2118e1f53f6f0973a1d9a6a7dc9296959bf39ec0;p=linux.git

posix-timers: Noralize good_sigevent

In good_sigevent directly compute the default return value as
"task_tgid(current)".  This is exactly the same as
"task_pid(current->group_leader)" but written more clearly.

In the thread case first compute the thread's pid.  Then veify that
attached to that pid is a thread of the current thread group.

This has the net effect of making the code a little clearer, and
making it obvious that posix timers never look up a process by a the
pid of a thread.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index e08ce3f274473..2bdf08a2bae96 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -433,11 +433,13 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 
 static struct pid *good_sigevent(sigevent_t * event)
 {
-	struct task_struct *rtn = current->group_leader;
+	struct pid *pid = task_tgid(current);
+	struct task_struct *rtn;
 
 	switch (event->sigev_notify) {
 	case SIGEV_SIGNAL | SIGEV_THREAD_ID:
-		rtn = find_task_by_vpid(event->sigev_notify_thread_id);
+		pid = find_vpid(event->sigev_notify_thread_id);
+		rtn = pid_task(pid, PIDTYPE_PID);
 		if (!rtn || !same_thread_group(rtn, current))
 			return NULL;
 		/* FALLTHRU */
@@ -447,7 +449,7 @@ static struct pid *good_sigevent(sigevent_t * event)
 			return NULL;
 		/* FALLTHRU */
 	case SIGEV_NONE:
-		return task_pid(rtn);
+		return pid;
 	default:
 		return NULL;
 	}