diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-06-26 00:26:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-26 09:58:27 -0700 |
| commit | 7b1c6154fa8bb937e0b1b4f2adbb315d70270f10 (patch) | |
| tree | 1d58e5e7da61330639ebe62671fb666596d1b00a | |
| parent | d5f70c00ad24cd1158d3678b44ff969b4c971d49 (diff) | |
[PATCH] coredump: don't take tasklist_lock
This patch removes tasklist_lock from zap_threads().
This is safe wrt:
do_exit:
The caller holds mm->mmap_sem. This means that task which
shares the same ->mm can't pass exit_mm(), so it can't be
unhashed from init_task.tasks or ->thread_group lists.
fork:
None of sub-threads can fork after zap_process(leader). All
processes which were created before this point should be
visible to zap_threads() because copy_process() adds the new
process to the tail of init_task.tasks list, and ->siglock
lock/unlock provides a memory barrier.
de_thread:
It does list_replace_rcu(&leader->tasks, ¤t->tasks).
So zap_threads() will see either old or new leader, it does
not matter. However, it can change p->sighand, so we should
use lock_task_sighand() in zap_process().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "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 | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/fs/exec.c b/fs/exec.c index b58ba7d127e0..49fa0127a330 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1373,7 +1373,11 @@ static void zap_process(struct task_struct *start) struct task_struct *t; unsigned long flags; - spin_lock_irqsave(&start->sighand->siglock, flags); + /* + * start->sighand can't disappear, but may be + * changed by de_thread() + */ + lock_task_sighand(start, &flags); start->signal->flags = SIGNAL_GROUP_EXIT; start->signal->group_stop_count = 0; @@ -1386,7 +1390,7 @@ static void zap_process(struct task_struct *start) } } while ((t = next_thread(t)) != start); - spin_unlock_irqrestore(&start->sighand->siglock, flags); + unlock_task_sighand(start, &flags); } static void zap_threads(struct mm_struct *mm) @@ -1404,7 +1408,7 @@ static void zap_threads(struct mm_struct *mm) complete(vfork_done); } - read_lock(&tasklist_lock); + rcu_read_lock(); for_each_process(g) { p = g; do { @@ -1415,7 +1419,7 @@ static void zap_threads(struct mm_struct *mm) } } while ((p = next_thread(p)) != g); } - read_unlock(&tasklist_lock); + rcu_read_unlock(); } static void coredump_wait(struct mm_struct *mm) |