Merge tag 'omap-for-v3.19/fixes-rc1' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-microblaze.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 1ea4369..6806c55 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1287,9 +1287,15 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 static int wait_consider_task(struct wait_opts *wo, int ptrace,
                                struct task_struct *p)
 {
+       /*
+        * We can race with wait_task_zombie() from another thread.
+        * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
+        * can't confuse the checks below.
+        */
+       int exit_state = ACCESS_ONCE(p->exit_state);
        int ret;
 
-       if (unlikely(p->exit_state == EXIT_DEAD))
+       if (unlikely(exit_state == EXIT_DEAD))
                return 0;
 
        ret = eligible_child(wo, p);
@@ -1310,7 +1316,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
                return 0;
        }
 
-       if (unlikely(p->exit_state == EXIT_TRACE)) {
+       if (unlikely(exit_state == EXIT_TRACE)) {
                /*
                 * ptrace == 0 means we are the natural parent. In this case
                 * we should clear notask_error, debugger will notify us.
@@ -1337,7 +1343,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
        }
 
        /* slay zombie? */
-       if (p->exit_state == EXIT_ZOMBIE) {
+       if (exit_state == EXIT_ZOMBIE) {
                /* we don't reap group leaders with subthreads */
                if (!delay_group_leader(p)) {
                        /*