diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2009-06-17 16:27:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-18 13:03:53 -0700 |
| commit | f95d39d10fe7d47336e65172f52bf64e0096f983 (patch) | |
| tree | 14b469b68455968dfd707695083ece72287dfaab /kernel/exit.c | |
| parent | a3f6dfb7295facb0505b5beca5a7ce48b0612379 (diff) | |
| download | lwn-f95d39d10fe7d47336e65172f52bf64e0096f983.tar.gz lwn-f95d39d10fe7d47336e65172f52bf64e0096f983.zip | |
do_wait: fix the theoretical race with stop/trace/cont
do_wait:
current->state = TASK_INTERRUPTIBLE;
read_lock(&tasklist_lock);
... search for the task to reap ...
In theory, the ->state changing can leak into the critical section. Since
the child can change its status under read_lock(tasklist) in parallel
(finish_stop/ptrace_stop), we can miss the wakeup if __wake_up_parent()
sees us in TASK_RUNNING state. Add the barrier.
Also, use __set_current_state() to set TASK_RUNNING.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index dd83c8419101..7ef355dd3dca 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1581,7 +1581,7 @@ repeat: (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) goto notask; - current->state = TASK_INTERRUPTIBLE; + set_current_state(TASK_INTERRUPTIBLE); read_lock(&tasklist_lock); tsk = current; do { @@ -1608,7 +1608,7 @@ notask: } } end: - current->state = TASK_RUNNING; + __set_current_state(TASK_RUNNING); remove_wait_queue(¤t->signal->wait_chldexit,&wait); if (wo->wo_info) { struct siginfo __user *infop = wo->wo_info; |