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author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-03-28 16:10:59 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-28 18:36:40 -0800 |
commit | 1434261c07bcebd5ef8b8a18f919fdee533b84e0 (patch) | |
tree | 1d0ba868866354569d2b8854a26ff48dbdbc1a98 | |
parent | fef23e7fbb11a0a78cd61935f7056bc2b237995a (diff) | |
download | op-kernel-dev-1434261c07bcebd5ef8b8a18f919fdee533b84e0.zip op-kernel-dev-1434261c07bcebd5ef8b8a18f919fdee533b84e0.tar.gz |
[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.c | 22 |
1 files changed, 10 insertions, 12 deletions
@@ -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(); |