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>
This commit is contained in:
Eric W. Biederman 2018-07-21 00:00:29 -05:00
parent 019191342f
commit 2118e1f53f

View file

@ -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;
}