diff options
| author |   Kirill Tkhai <ktkhai@parallels.com> | 2015-04-16 12:48:01 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-17 09:04:07 -0400 |
| commit | dfcce791fb0ad06f3f0b745a23160b9d8858fe39 (patch) | |
| tree | a3c49070946f205a96642688af0daf5cd3c3c432 /fs/exec.c | |
| parent | prctl: avoid using mmap_sem for exe_file serialization (diff) | |
| download | linux-dev-dfcce791fb0ad06f3f0b745a23160b9d8858fe39.tar.xz linux-dev-dfcce791fb0ad06f3f0b745a23160b9d8858fe39.zip | |
fs/exec.c:de_thread: move notify_count write under lock
We set sig->notify_count = -1 between RELEASE and ACQUIRE operations:
spin_unlock_irq(lock);
...
if (!thread_group_leader(tsk)) {
...
for (;;) {
sig->notify_count = -1;
write_lock_irq(&tasklist_lock);
There are no restriction on it so other processors may see this STORE
mixed with other STOREs in both areas limited by the spinlocks.
Probably, it may be reordered with the above
sig->group_exit_task = tsk;
sig->notify_count = zap_other_threads(tsk);
in some way.
Set it under tasklist_lock locked to be sure nothing will be reordered.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
| -rw-r--r-- | fs/exec.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c index a5fef835ebc5..02bfd980a40c 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -926,10 +926,14 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) { struct task_struct *leader = tsk->group_leader; - sig->notify_count = -1; /* for exit_notify() */ for (;;) { threadgroup_change_begin(tsk); write_lock_irq(&tasklist_lock); + /* + * Do this under tasklist_lock to ensure that + * exit_notify() can't miss ->group_exit_task + */ + sig->notify_count = -1; if (likely(leader->exit_state)) break; __set_current_state(TASK_KILLABLE); |