diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-04-30 07:52:51 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 15:29:35 (GMT) |
| commit | 08d2c30ce98d274137f12b0a9b9c74137455922c (patch) | |
| tree | cc649fd249aef0c4d227406b17a1a75c9d327e50 | |
| parent | 3547ff3aefbe092ca35506c60c02e2d17a4f2199 (diff) | |
| download | linux-08d2c30ce98d274137f12b0a9b9c74137455922c.tar.xz | |
signals: send_sig_info: don't take tasklist_lock
The comment in send_sig_info() is wrong, tasklist_lock can't help.
The caller must ensure the task can't go away, otherwise ->sighand can be NULL
even before we take the lock.
p->sighand could be changed by exec(), but I can't imagine how it is possible
to prevent exit(), but not exec().
Since the things seem to work, I assume all callers are correct. However,
drm_vbl_send_signals() looks broken. block_all_signals() which is solely used
by drm is definitely broken.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/signal.c | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 13371d1..17859f0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1138,8 +1138,7 @@ static int kill_something_info(int sig, struct siginfo *info, int pid) */ /* - * These two are the most common entry points. They send a signal - * just to the specific thread. + * The caller must ensure the task can't exit. */ int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) @@ -1154,17 +1153,9 @@ send_sig_info(int sig, struct siginfo *info, struct task_struct *p) if (!valid_signal(sig)) return -EINVAL; - /* - * We need the tasklist lock even for the specific - * thread case (when we don't need to follow the group - * lists) in order to avoid races with "p->sighand" - * going away or changing from under us. - */ - read_lock(&tasklist_lock); spin_lock_irqsave(&p->sighand->siglock, flags); ret = specific_send_sig_info(sig, info, p); spin_unlock_irqrestore(&p->sighand->siglock, flags); - read_unlock(&tasklist_lock); return ret; } |