1 files changed, 15 insertions, 25 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 019a2843bf95..ceffc67b564a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -58,11 +58,11 @@
 
 static void exit_mm(struct task_struct * tsk);
 
-static void __unhash_process(struct task_struct *p)
+static void __unhash_process(struct task_struct *p, bool group_dead)
 {
         nr_threads--;
         detach_pid(p, PIDTYPE_PID);
-        if (thread_group_leader(p)) {
+        if (group_dead) {
                 detach_pid(p, PIDTYPE_PGID);
                 detach_pid(p, PIDTYPE_SID);
 
@@ -79,10 +79,9 @@ static void __unhash_process(struct task_struct *p)
 static void __exit_signal(struct task_struct *tsk)
 {
         struct signal_struct *sig = tsk->signal;
+        bool group_dead = thread_group_leader(tsk);
         struct sighand_struct *sighand;
-
-        BUG_ON(!sig);
-        BUG_ON(!atomic_read(&sig->count));
+        struct tty_struct *uninitialized_var(tty);
 
         sighand = rcu_dereference_check(tsk->sighand,
                                         rcu_read_lock_held() ||
@@ -90,14 +89,16 @@ static void __exit_signal(struct task_struct *tsk)
         spin_lock(&sighand->siglock);
 
         posix_cpu_timers_exit(tsk);
-        if (atomic_dec_and_test(&sig->count))
+        if (group_dead) {
                 posix_cpu_timers_exit_group(tsk);
-        else {
+                tty = sig->tty;
+                sig->tty = NULL;
+        } else {
                 /*
                  * If there is any task waiting for the group exit
                  * then notify it:
                  */
-                if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
+                if (sig->notify_count > 0 && !--sig->notify_count)
                         wake_up_process(sig->group_exit_task);
 
                 if (tsk == sig->curr_target)
@@ -123,32 +124,24 @@ static void __exit_signal(struct task_struct *tsk)
                 sig->oublock += task_io_get_oublock(tsk);
                 task_io_accounting_add(&sig->ioac, &tsk->ioac);
                 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
-                sig = NULL; /* Marker for below. */
         }
 
-        __unhash_process(tsk);
+        sig->nr_threads--;
+        __unhash_process(tsk, group_dead);
 
         /*
          * Do this under ->siglock, we can race with another thread
          * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
          */
         flush_sigqueue(&tsk->pending);
-
-        tsk->signal = NULL;
         tsk->sighand = NULL;
         spin_unlock(&sighand->siglock);
 
         __cleanup_sighand(sighand);
         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
-        if (sig) {
+        if (group_dead) {
                 flush_sigqueue(&sig->shared_pending);
-                taskstats_tgid_free(sig);
-                /*
-                 * Make sure ->signal can't go away under rq->lock,
-                 * see account_group_exec_runtime().
-                 */
-                task_rq_unlock_wait(tsk);
-                __cleanup_signal(sig);
+                tty_kref_put(tty);
         }
 }
 
@@ -856,12 +849,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 
         tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
 
-        /* mt-exec, de_thread() is waiting for us */
-        if (thread_group_leader(tsk) &&
-            tsk->signal->group_exit_task &&
-            tsk->signal->notify_count < 0)
+        /* mt-exec, de_thread() is waiting for group leader */
+        if (unlikely(tsk->signal->notify_count < 0))
                 wake_up_process(tsk->signal->group_exit_task);
-
         write_unlock_irq(&tasklist_lock);
 
         tracehook_report_death(tsk, signal, cookie, group_dead);