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authorOleg Nesterov <oleg@tv-sign.ru>2007-05-09 02:34:37 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 12:30:53 -0700
commit10ab825bdef8df510f99c703a5a2d9b13a4e31a5 (patch)
treee4db81f26c03ba5a5bff43ed44646a4ed4509d67 /kernel/signal.c
parent5de18d169739293e27e0cf9acfc75a2d2f4aa572 (diff)
downloadop-kernel-dev-10ab825bdef8df510f99c703a5a2d9b13a4e31a5.zip
op-kernel-dev-10ab825bdef8df510f99c703a5a2d9b13a4e31a5.tar.gz
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>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 23ae6d6..2ac3a66 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.
*/
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