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authorOleg Nesterov <oleg@redhat.com>2012-03-19 17:03:22 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 14:16:50 -0700
commite636825346b36a07ccfc8e30946d52855e21f681 (patch)
tree128c37b3102223a95ce03b856766c33e4d077114 /fs/exec.c
parent5f8aadd8b9966d71a77bba52b9d499cc2f38269f (diff)
downloadop-kernel-dev-e636825346b36a07ccfc8e30946d52855e21f681.zip
op-kernel-dev-e636825346b36a07ccfc8e30946d52855e21f681.tar.gz
exit_signal: simplify the "we have changed execution domain" logic
exit_notify() checks "tsk->self_exec_id != tsk->parent_exec_id" to handle the "we have changed execution domain" case. We can change do_thread() to always set ->exit_signal = SIGCHLD and remove this check to simplify the code. We could change setup_new_exec() instead, this looks more logical because it increments ->self_exec_id. But note that de_thread() already resets ->exit_signal if it changes the leader, let's keep both changes close to each other. Note that we change ->exit_signal lockless, this changes the rules. Thereafter ->exit_signal is not stable under tasklist but this is fine, the only possible change is OLDSIG -> SIGCHLD. This can race with eligible_child() but the race is harmless. We can race with reparent_leader() which changes our ->exit_signal in parallel, but it does the same change to SIGCHLD. The noticeable user-visible change is that the execing task is not "visible" to do_wait()->eligible_child(__WCLONE) right after exec. To me this looks more logical, and this is consistent with mt case. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c
index b0695a9..1e94d22 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -977,6 +977,9 @@ static int de_thread(struct task_struct *tsk)
sig->notify_count = 0;
no_thread_group:
+ /* we have changed execution domain */
+ tsk->exit_signal = SIGCHLD;
+
if (current->mm)
setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
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