Revert "Fix cpu timers exit deadlock and races"
Revert commit e03d13e985d48ac4885382c9e3b1510c78bd047f, to be replaced
by a much nicer fix from Roland.
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b3f3edc..7a51a55 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -387,19 +387,25 @@
if (unlikely(p == NULL))
return 0;
- spin_lock(&p->sighand->siglock);
if (!list_empty(&timer->it.cpu.entry)) {
- /*
- * Take us off the task's timer list. We don't need to
- * take tasklist_lock and check for the task being reaped.
- * If it was reaped, it already called posix_cpu_timers_exit
- * and posix_cpu_timers_exit_group to clear all the timers
- * that pointed to it.
- */
- list_del(&timer->it.cpu.entry);
- put_task_struct(p);
+ read_lock(&tasklist_lock);
+ if (unlikely(p->signal == NULL)) {
+ /*
+ * We raced with the reaping of the task.
+ * The deletion should have cleared us off the list.
+ */
+ BUG_ON(!list_empty(&timer->it.cpu.entry));
+ } else {
+ /*
+ * Take us off the task's timer list.
+ */
+ spin_lock(&p->sighand->siglock);
+ list_del(&timer->it.cpu.entry);
+ spin_unlock(&p->sighand->siglock);
+ }
+ read_unlock(&tasklist_lock);
}
- spin_unlock(&p->sighand->siglock);
+ put_task_struct(p);
return 0;
}
