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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 /kernel/exit.c
parent5f8aadd8b9966d71a77bba52b9d499cc2f38269f (diff)
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 'kernel/exit.c')
-rw-r--r--kernel/exit.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 752d2c0abd19..51ac4ced1313 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -827,14 +827,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
* If the parent exec id doesn't match the exec id we saved
* when we started then we know the parent has changed security
* domain.
- *
- * If our self_exec id doesn't match our parent_exec_id then
- * we have changed execution domain as these two values started
- * the same after a fork.
*/
if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
- (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
- tsk->self_exec_id != tsk->parent_exec_id))
+ tsk->parent_exec_id != tsk->real_parent->self_exec_id)
tsk->exit_signal = SIGCHLD;
if (unlikely(tsk->ptrace)) {