Messages in this thread | | | From | Roland McGrath <> | Subject | Re: [BUG] ptraced process waiting on syscall may return kernel internal errnos | Date | Wed, 13 Jun 2007 16:01:53 -0700 (PDT) |
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> The freezer is crap... news at 11. Maybe a quick hack would be to let it > clear sigpending if tsk->mm == NULL but that's ugly. Note that there's > anything pretty about the freezer anyway...
I think it might be made not too unreasonable by adding a TASK_FROZEN state. But I am still persuaded by my "hide in the corner" plan.
> Well.. why was it _and_wake() in the first place anyway ? Or do I miss > something ? Why would we need to wake a thread for which we are removing > signals ?
The bug was about a case where recalc_sigpending_tsk would set TIF_SIGPENDING when it hadn't been set before (wants_signal). It has nothing to do with the rm_from_queue_full being done there. It's just a violation of the necessary rule that when you set TIF_SIGPENDING on another thread you better call signal_wake_up on it.
> What about something like: > > do { > rm_from_queue_full(&mask, &t->pending); > - recalc_sigpending_and_wake(t); > t = next_thread(t); > } while (t != current); > + recalc_sigpending();
There is no need for the +, just the -. The calling thread is the one where know there is certainly no perturbation of behavior due to leaving TIF_SIGPENDING set rather than clearing it. It's just going to exit the syscall and deal with signal state properly on the way out either way. Doing recalc_sigpending is an unnecessary optimization of the corner case.
> So at the end of the day, easier to test it inside dequeue_signal().
Before completely revamping the whole set of entrypoints to be saner all around, yes.
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