This is a note to let you know that I've just added the patch titled
exit_signal: simplify the "we have changed execution domain" logic
to the 3.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
exit_signal-simplify-the-we-have-changed-execution-domain-logic.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From e636825346b36a07ccfc8e30946d52855e21f681 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Mon, 19 Mar 2012 17:03:22 +0100
Subject: exit_signal: simplify the "we have changed execution domain" logic
From: Oleg Nesterov <[email protected]>
commit e636825346b36a07ccfc8e30946d52855e21f681 upstream.
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 <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/exec.c | 3 +++
kernel/exit.c | 7 +------
2 files changed, 4 insertions(+), 6 deletions(-)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -975,6 +975,9 @@ static int de_thread(struct task_struct
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);
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -827,14 +827,9 @@ static void exit_notify(struct task_stru
* 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)) {
Patches currently in stable-queue which might be from [email protected] are
queue-3.3/exit_signal-simplify-the-we-have-changed-execution-domain-logic.patch
queue-3.3/i387-ptrace-breaks-the-lazy-fpu-restore-logic.patch
queue-3.3/exit_signal-fix-the-parent-has-changed-security-domain-logic.patch
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