Messages in this thread Patch in this message | | | Subject | Re: [BUG] ptraced process waiting on syscall may return kernel internal errnos | From | Benjamin Herrenschmidt <> | Date | Thu, 14 Jun 2007 08:36:00 +1000 |
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On Wed, 2007-06-13 at 19:15 +0400, Oleg Nesterov wrote: > > This breaks cancel_freezing(). Somehow we should clear TIF_SIGPENDING > for kernel threads. Otherwise we may have subtle failures if > try_to_freeze_tasks() fails.
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...
> Also, whith this change do_sigaction()->recalc_sigpending_and_wake() > doesn't make sense any longer, yes?
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 ?
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();
> > @@ -385,7 +391,8 @@ int dequeue_signal(struct task_struct *t > > } > > } > > } > > - recalc_sigpending_tsk(tsk); > > + if (likely(tsk == current)) > > + recalc_sigpending(); > > In theory, flush_signals(t) needs a similar change. However, it is > always > called with t == current. Perhaps it makes sense to make it > flush_signals(void) ?
Agreed.
> Do you see any valid usage of flush_signals(t) when t != current ? > > (Actually, imho the same is true for dequeue_signal(). Except for > signalfd.c > dequeue_signal() should operate on current. Perhaps it would be a bit > cleaner > to have dequeue_signal_tsk(tsk) and dequeue_signal(void), the latter > does > recalc_sigpending).
That's been part of the discussion so far ... so yes, maybe. I also think dequeue_signal_tsk would then only dequeue shared signals... But then, that means signalfd would have to do a if (tsk == current) to know which one to call...
So at the end of the day, easier to test it inside dequeue_signal().
Ben.
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