Make sure SIGKILL gets proper respect
Bhavesh P. Davda <bhavesh@avaya.com> noticed that SIGKILL wouldn't properly kill a process under just the right cicumstances: a stopped task that already had another signal queued would get the SIGKILL queued onto the shared queue, and there it would remain until SIGCONT. This simplifies the signal acceptance logic, and fixes the bug in the process. Losely based on an earlier patch by Bhavesh. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -936,34 +936,31 @@ force_sig_specific(int sig, struct task_struct *t)
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* as soon as they're available, so putting the signal on the shared queue
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* will be equivalent to sending it to one such thread.
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*/
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#define wants_signal(sig, p, mask) \
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(!sigismember(&(p)->blocked, sig) \
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&& !((p)->state & mask) \
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&& !((p)->flags & PF_EXITING) \
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&& (task_curr(p) || !signal_pending(p)))
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static inline int wants_signal(int sig, struct task_struct *p)
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{
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if (sigismember(&p->blocked, sig))
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return 0;
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if (p->flags & PF_EXITING)
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return 0;
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if (sig == SIGKILL)
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return 1;
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if (p->state & (TASK_STOPPED | TASK_TRACED))
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return 0;
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return task_curr(p) || !signal_pending(p);
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}
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static void
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__group_complete_signal(int sig, struct task_struct *p)
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{
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unsigned int mask;
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struct task_struct *t;
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/*
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* Don't bother traced and stopped tasks (but
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* SIGKILL will punch through that).
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*/
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mask = TASK_STOPPED | TASK_TRACED;
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if (sig == SIGKILL)
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mask = 0;
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/*
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* Now find a thread we can wake up to take the signal off the queue.
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*
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* If the main thread wants the signal, it gets first crack.
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* Probably the least surprising to the average bear.
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*/
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if (wants_signal(sig, p, mask))
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if (wants_signal(sig, p))
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t = p;
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else if (thread_group_empty(p))
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/*
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@ -981,7 +978,7 @@ __group_complete_signal(int sig, struct task_struct *p)
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t = p->signal->curr_target = p;
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BUG_ON(t->tgid != p->tgid);
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while (!wants_signal(sig, t, mask)) {
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while (!wants_signal(sig, t)) {
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t = next_thread(t);
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if (t == p->signal->curr_target)
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/*
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