diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2007-05-09 02:34:37 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-09 12:30:53 -0700 |
| commit | 10ab825bdef8df510f99c703a5a2d9b13a4e31a5 (patch) | |
| tree | e4db81f26c03ba5a5bff43ed44646a4ed4509d67 | |
| parent | 5de18d169739293e27e0cf9acfc75a2d2f4aa572 (diff) | |
change kernel threads to ignore signals instead of blocking them
Currently kernel threads use sigprocmask(SIG_BLOCK) to protect against
signals. This doesn't prevent the signal delivery, this only blocks
signal_wake_up(). Every "killall -33 kthreadd" means a "struct siginfo"
leak.
Change kthreadd_setup() to set all handlers to SIG_IGN instead of blocking
them (make a new helper ignore_signals() for that). If the kernel thread
needs some signal, it should use allow_signal() anyway, and in that case it
should not use CLONE_SIGHAND.
Note that we can't change daemonize() (should die!) in the same way,
because it can be used along with CLONE_SIGHAND. This means that
allow_signal() still should unblock the signal to work correctly with
daemonize()ed threads.
However, disallow_signal() doesn't block the signal any longer but ignores
it.
NOTE: with or without this patch the kernel threads are not protected from
handle_stop_signal(), this seems harmless, but not good.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/sched.h | 1 | ||||
| -rw-r--r-- | kernel/exit.c | 2 | ||||
| -rw-r--r-- | kernel/kthread.c | 17 | ||||
| -rw-r--r-- | kernel/signal.c | 10 |
4 files changed, 15 insertions, 15 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 3d95c480f58d..28000b1658f9 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1317,6 +1317,7 @@ extern int in_egroup_p(gid_t); extern void proc_caches_init(void); extern void flush_signals(struct task_struct *); +extern void ignore_signals(struct task_struct *); extern void flush_signal_handlers(struct task_struct *, int force_default); extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info); diff --git a/kernel/exit.c b/kernel/exit.c index bc982cd72743..b0c6f0c3a2df 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -347,7 +347,7 @@ int disallow_signal(int sig) return -EINVAL; spin_lock_irq(¤t->sighand->siglock); - sigaddset(¤t->blocked, sig); + current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); return 0; diff --git a/kernel/kthread.c b/kernel/kthread.c index 0eb0070a3c57..df8a8e8f6ca4 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -215,24 +215,13 @@ EXPORT_SYMBOL(kthread_stop); static __init void kthreadd_setup(void) { struct task_struct *tsk = current; - struct k_sigaction sa; - sigset_t blocked; set_task_comm(tsk, "kthreadd"); - /* Block and flush all signals */ - sigfillset(&blocked); - sigprocmask(SIG_BLOCK, &blocked, NULL); - flush_signals(tsk); + ignore_signals(tsk); - /* SIG_IGN makes children autoreap: see do_notify_parent(). */ - sa.sa.sa_handler = SIG_IGN; - sa.sa.sa_flags = 0; - siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD)); - do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0); - - set_user_nice(current, -5); - set_cpus_allowed(current, CPU_MASK_ALL); + set_user_nice(tsk, -5); + set_cpus_allowed(tsk, CPU_MASK_ALL); } int kthreadd(void *unused) diff --git a/kernel/signal.c b/kernel/signal.c index 23ae6d62fc41..2ac3a668d9dd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -209,6 +209,16 @@ void flush_signals(struct task_struct *t) spin_unlock_irqrestore(&t->sighand->siglock, flags); } +void ignore_signals(struct task_struct *t) +{ + int i; + + for (i = 0; i < _NSIG; ++i) + t->sighand->action[i].sa.sa_handler = SIG_IGN; + + flush_signals(t); +} + /* * Flush all handlers for a task. */ |