1 files changed, 47 insertions, 93 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index d3c66b53dff6..b931d7cedbfa 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -313,6 +313,7 @@ void do_schedule_next_timer(struct siginfo *info)
 
 int posix_timer_event(struct k_itimer *timr, int si_private)
 {
+        int shared, ret;
         /*
          * FIXME: if ->sigq is queued we can race with
          * dequeue_signal()->do_schedule_next_timer().
@@ -326,25 +327,10 @@ int posix_timer_event(struct k_itimer *timr, int si_private)
          */
         timr->sigq->info.si_sys_private = si_private;
 
-        timr->sigq->info.si_signo = timr->it_sigev_signo;
-        timr->sigq->info.si_code = SI_TIMER;
-        timr->sigq->info.si_tid = timr->it_id;
-        timr->sigq->info.si_value = timr->it_sigev_value;
-
-        if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
-                struct task_struct *leader;
-                int ret = send_sigqueue(timr->sigq, timr->it_process, 0);
-
-                if (likely(ret >= 0))
-                        return ret;
-
-                timr->it_sigev_notify = SIGEV_SIGNAL;
-                leader = timr->it_process->group_leader;
-                put_task_struct(timr->it_process);
-                timr->it_process = leader;
-        }
-
-        return send_sigqueue(timr->sigq, timr->it_process, 1);
+        shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
+        ret = send_sigqueue(timr->sigq, timr->it_process, shared);
+        /* If we failed to send the signal the timer stops. */
+        return ret > 0;
 }
 EXPORT_SYMBOL_GPL(posix_timer_event);
 
@@ -456,7 +442,7 @@ static struct k_itimer * alloc_posix_timer(void)
                 return tmr;
         if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
                 kmem_cache_free(posix_timers_cache, tmr);
-                tmr = NULL;
+                return NULL;
         }
         memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
         return tmr;
@@ -483,11 +469,9 @@ sys_timer_create(const clockid_t which_clock,
                  struct sigevent __user *timer_event_spec,
                  timer_t __user * created_timer_id)
 {
-        int error = 0;
-        struct k_itimer *new_timer = NULL;
-        int new_timer_id;
-        struct task_struct *process = NULL;
-        unsigned long flags;
+        struct k_itimer *new_timer;
+        int error, new_timer_id;
+        struct task_struct *process;
         sigevent_t event;
         int it_id_set = IT_ID_NOT_SET;
 
@@ -505,12 +489,11 @@ 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 == -EAGAIN)
-                goto retry;
-        else if (error) {
+        if (error) {
+                if (error == -EAGAIN)
+                        goto retry;
                 /*
                  * Weird looking, but we return EAGAIN if the IDR is
                  * full (proper POSIX return value for this)
@@ -541,67 +524,43 @@ sys_timer_create(const clockid_t which_clock,
                         error = -EFAULT;
                         goto out;
                 }
-                new_timer->it_sigev_notify = event.sigev_notify;
-                new_timer->it_sigev_signo = event.sigev_signo;
-                new_timer->it_sigev_value = event.sigev_value;
-
-                read_lock(&tasklist_lock);
-                if ((process = good_sigevent(&event))) {
-                        /*
-                         * We may be setting up this process for another
-                         * thread.  It may be exiting.  To catch this
-                         * case the we check the PF_EXITING flag.  If
-                         * the flag is not set, the siglock will catch
-                         * him before it is too late (in exit_itimers).
-                         *
-                         * The exec case is a bit more invloved but easy
-                         * to code.  If the process is in our thread
-                         * group (and it must be or we would not allow
-                         * it here) and is doing an exec, it will cause
-                         * us to be killed.  In this case it will wait
-                         * for us to die which means we can finish this
-                         * linkage with our last gasp. I.e. no code :)
-                         */
-                        spin_lock_irqsave(&process->sighand->siglock, flags);
-                        if (!(process->flags & PF_EXITING)) {
-                                new_timer->it_process = process;
-                                list_add(&new_timer->list,
-                                         &process->signal->posix_timers);
-                                if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-                                        get_task_struct(process);
-                                spin_unlock_irqrestore(&process->sighand->siglock, flags);
-                        } else {
-                                spin_unlock_irqrestore(&process->sighand->siglock, flags);
-                                process = NULL;
-                        }
-                }
-                read_unlock(&tasklist_lock);
+                rcu_read_lock();
+                process = good_sigevent(&event);
+                if (process)
+                        get_task_struct(process);
+                rcu_read_unlock();
                 if (!process) {
                         error = -EINVAL;
                         goto out;
                 }
         } else {
-                new_timer->it_sigev_notify = SIGEV_SIGNAL;
-                new_timer->it_sigev_signo = SIGALRM;
-                new_timer->it_sigev_value.sival_int = new_timer->it_id;
+                event.sigev_notify = SIGEV_SIGNAL;
+                event.sigev_signo = SIGALRM;
+                event.sigev_value.sival_int = new_timer->it_id;
                 process = current->group_leader;
-                spin_lock_irqsave(&process->sighand->siglock, flags);
-                new_timer->it_process = process;
-                list_add(&new_timer->list, &process->signal->posix_timers);
-                spin_unlock_irqrestore(&process->sighand->siglock, flags);
+                get_task_struct(process);
         }
 
+        new_timer->it_sigev_notify     = event.sigev_notify;
+        new_timer->sigq->info.si_signo = event.sigev_signo;
+        new_timer->sigq->info.si_value = event.sigev_value;
+        new_timer->sigq->info.si_tid   = new_timer->it_id;
+        new_timer->sigq->info.si_code  = SI_TIMER;
+
+        spin_lock_irq(&current->sighand->siglock);
+        new_timer->it_process = process;
+        list_add(&new_timer->list, &current->signal->posix_timers);
+        spin_unlock_irq(&current->sighand->siglock);
+
+        return 0;
         /*
          * In the case of the timer belonging to another task, after
          * the task is unlocked, the timer is owned by the other task
          * and may cease to exist at any time.  Don't use or modify
          * new_timer after the unlock call.
          */
-
 out:
-        if (error)
-                release_posix_timer(new_timer, it_id_set);
-
+        release_posix_timer(new_timer, it_id_set);
         return error;
 }
 
@@ -612,7 +571,7 @@ out:
  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
  * be release with out holding the timer lock.
  */
-static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
+static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
 {
         struct k_itimer *timr;
         /*
@@ -620,23 +579,20 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
          * flags part over to the timer lock.  Must not let interrupts in
          * while we are moving the lock.
          */
-
         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)) {
-                        spin_unlock(&timr->it_lock);
-                        spin_unlock_irqrestore(&idr_lock, *flags);
-                        timr = NULL;
-                } else
+                if (timr->it_process &&
+                    same_thread_group(timr->it_process, current)) {
                         spin_unlock(&idr_lock);
-        } else
-                spin_unlock_irqrestore(&idr_lock, *flags);
+                        return timr;
+                }
+                spin_unlock(&timr->it_lock);
+        }
+        spin_unlock_irqrestore(&idr_lock, *flags);
 
-        return timr;
+        return NULL;
 }
 
 /*
@@ -877,8 +833,7 @@ retry_delete:
          * This keeps any tasks waiting on the spin lock from thinking
          * they got something (see the lock code above).
          */
-        if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-                put_task_struct(timer->it_process);
+        put_task_struct(timer->it_process);
         timer->it_process = NULL;
 
         unlock_timer(timer, flags);
@@ -905,8 +860,7 @@ retry_delete:
          * This keeps any tasks waiting on the spin lock from thinking
          * they got something (see the lock code above).
          */
-        if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-                put_task_struct(timer->it_process);
+        put_task_struct(timer->it_process);
         timer->it_process = NULL;
 
         unlock_timer(timer, flags);