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authorOleg Nesterov <oleg@tv-sign.ru>2006-03-28 16:10:59 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-28 18:36:40 -0800
commit1434261c07bcebd5ef8b8a18f919fdee533b84e0 (patch)
tree1d0ba868866354569d2b8854a26ff48dbdbc1a98
parentfef23e7fbb11a0a78cd61935f7056bc2b237995a (diff)
[PATCH] simplify exec from init's subthread
I think it is enough to take tasklist_lock for reading while changing child_reaper: Reparenting needs write_lock(tasklist_lock) Only one thread in a thread group can do exec() sighand->siglock garantees that get_signal_to_deliver() will not see a stale value of child_reaper. This means that we can change child_reaper earlier, without calling zap_other_threads() twice. "child_reaper = current" is a NOOP when init does exec from main thread, we don't care. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/exec.c22
1 files changed, 10 insertions, 12 deletions
diff --git a/fs/exec.c b/fs/exec.c
index d0ecea0781f..dd194923c52 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -616,6 +616,15 @@ static int de_thread(struct task_struct *tsk)
kmem_cache_free(sighand_cachep, newsighand);
return -EAGAIN;
}
+
+ /*
+ * child_reaper ignores SIGKILL, change it now.
+ * Reparenting needs write_lock on tasklist_lock,
+ * so it is safe to do it under read_lock.
+ */
+ if (unlikely(current->group_leader == child_reaper))
+ child_reaper = current;
+
zap_other_threads(current);
read_unlock(&tasklist_lock);
@@ -660,23 +669,12 @@ static int de_thread(struct task_struct *tsk)
struct dentry *proc_dentry1, *proc_dentry2;
unsigned long ptrace;
- leader = current->group_leader;
- /*
- * If our leader is the child_reaper become
- * the child_reaper and resend SIGKILL signal.
- */
- if (unlikely(leader == child_reaper)) {
- write_lock(&tasklist_lock);
- child_reaper = current;
- zap_other_threads(current);
- write_unlock(&tasklist_lock);
- }
-
/*
* Wait for the thread group leader to be a zombie.
* It should already be zombie at this point, most
* of the time.
*/
+ leader = current->group_leader;
while (leader->exit_state != EXIT_ZOMBIE)
yield();