posix-timers: lock_timer: kill the bogus ->it_id check

lock_timer() checks that the timer found by idr_find(timer_id) has ->it_id
== timer_id.  This buys nothing.  This check can fail only if
sys_timer_create() unlocked idr_lock after idr_get_new(), but didn't set
->it_id = new_timer_id yet.  But in that case ->it_process == NULL so
lock_timer() can't succeed anyway.

Also remove a couple of unneeded typecasts.

Note that with or without this patch we have a small problem.
sys_timer_create() doesn't ensure that the result of setting (say)
->it_sigev_notify must be visible if lock_timer() succeeds.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 3eff47b..7185f05 100644 (file)
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -474,8 +474,7 @@ sys_timer_create(const clockid_t which_clock,
                goto out;
        }
        spin_lock_irq(&idr_lock);
-       error = idr_get_new(&posix_timers_id, (void *) new_timer,
-                           &new_timer_id);
+       error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
        spin_unlock_irq(&idr_lock);
        if (error) {
                if (error == -EAGAIN)
@@ -567,12 +566,12 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
         */
 
        spin_lock_irqsave(&idr_lock, *flags);
-       timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id);
+       timr = idr_find(&posix_timers_id, (int) timer_id);
        if (timr) {
                spin_lock(&timr->it_lock);
 
-               if ((timr->it_id != timer_id) || !(timr->it_process) ||
-                               !same_thread_group(timr->it_process, current)) {
+               if (!timr->it_process ||
+                   !same_thread_group(timr->it_process, current)) {
                        spin_unlock(&timr->it_lock);
                        spin_unlock_irqrestore(&idr_lock, *flags);
                        timr = NULL;