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authorOleg Nesterov <oleg@tv-sign.ru>2008-02-04 22:27:24 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:07 -0800
commited5d2cac114202fe2978a9cbcab8f5032796d538 (patch)
treeaa9aaea1aa0945bd9159685d1b04897d105a90c9 /kernel/signal.c
parentf558b7e408026eb3c6afcd0e8fc1f7fe31195a6a (diff)
downloadlwn-ed5d2cac114202fe2978a9cbcab8f5032796d538.tar.gz
lwn-ed5d2cac114202fe2978a9cbcab8f5032796d538.zip
exec: rework the group exit and fix the race with kill
As Roland pointed out, we have the very old problem with exec. de_thread() sets SIGNAL_GROUP_EXIT, kills other threads, changes ->group_leader and then clears signal->flags. All signals (even fatal ones) sent in this window (which is not too small) will be lost. With this patch exec doesn't abuse SIGNAL_GROUP_EXIT. signal_group_exit(), the new helper, should be used to detect exit_group() or exec() in progress. It can have more users, but this patch does only strictly necessary changes. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Robin Holt <holt@sgi.com> Cc: 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/signal.c')
-rw-r--r--kernel/signal.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 1117b28488c2..6a5f97cd337a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -957,7 +957,6 @@ void zap_other_threads(struct task_struct *p)
{
struct task_struct *t;
- p->signal->flags = SIGNAL_GROUP_EXIT;
p->signal->group_stop_count = 0;
for (t = next_thread(p); t != p; t = next_thread(t)) {
@@ -1697,7 +1696,8 @@ static int do_signal_stop(int signr)
} else {
struct task_struct *t;
- if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
+ if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
+ unlikely(sig->group_exit_task))
return 0;
/*
* There is no group stop already in progress.