On 04/25, Al Viro wrote: > > On Wed, Apr 25, 2012 at 02:37:46PM +0200, Oleg Nesterov wrote: > > As for sys_sigsuspend() and this race in particular: > > > > > Arrival of a signal that has userland handler > > > and that isn't blocked by the mask given to sigsuspend() should terminate > > > sigsuspend(). > > > > Yes. But note that do_signal() restores the old sigmask. This means that > > the signal we get after the first do_signal() was not blocked before > > sigsuspend() was called. So, to some extent, we can pretend that the > > handler was executed before sigsuspend() and it was never restarted. > > Signal might have already arrived by the time we restore sigmask. Yes, and it sets TIF_SIGPENDING, but unless I missed something this doesn't matter. > So no, > it might have been blocked prior to sigsuspend(). If it was not blocked, then the next do_signal()->get_signal_to_deliver() returns 0 and clears TIF_SIGPENDING. After that we finally re-enter sys_sigsuspend() and (assuming it unblocks this sig) notice this pending signal again and return -EINTR eventually. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
