[tip: timers/core] posix-cpu-timers: Use common permission check in posix_cpu_timer_create()

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     e5a8b65b4cb2fe024b83bdec0424269949cc0a27
Gitweb:        https://git.kernel.org/tip/e5a8b65b4cb2fe024b83bdec0424269949cc0a27
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Wed, 21 Aug 2019 21:08:50 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 28 Aug 2019 11:50:25 +02:00

posix-cpu-timers: Use common permission check in posix_cpu_timer_create()

Yet another copy of the same thing gone...

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190821192919.505833418@xxxxxxxxxxxxx

---
 kernel/time/posix-cpu-timers.c | 35 ++-------------------------------
 1 file changed, 3 insertions(+), 32 deletions(-)

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index eb11117..4426a0f 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -316,44 +316,15 @@ static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
  */
 static int posix_cpu_timer_create(struct k_itimer *new_timer)
 {
-	int ret = 0;
-	const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
-	struct task_struct *p;
+	struct task_struct *p = get_task_for_clock(new_timer->it_clock);
 
-	if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
+	if (!p)
 		return -EINVAL;
 
 	new_timer->kclock = &clock_posix_cpu;
-
 	INIT_LIST_HEAD(&new_timer->it.cpu.entry);
-
-	rcu_read_lock();
-	if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
-		if (pid == 0) {
-			p = current;
-		} else {
-			p = find_task_by_vpid(pid);
-			if (p && !same_thread_group(p, current))
-				p = NULL;
-		}
-	} else {
-		if (pid == 0) {
-			p = current->group_leader;
-		} else {
-			p = find_task_by_vpid(pid);
-			if (p && !has_group_leader_pid(p))
-				p = NULL;
-		}
-	}
 	new_timer->it.cpu.task = p;
-	if (p) {
-		get_task_struct(p);
-	} else {
-		ret = -EINVAL;
-	}
-	rcu_read_unlock();
-
-	return ret;
+	return 0;
 }
 
 /*