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Date: Thu, 21 Jun 2007 22:23:40 +0400 From: Oleg Nesterov <oleg@...sign.ru> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>, Davide Libenzi <davidel@...ilserver.org>, Nicholas Miell <nmiell@...cast.net>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: Fix signalfd interaction with thread-private signals On 06/21, Linus Torvalds wrote: > > On Thu, 21 Jun 2007, Oleg Nesterov wrote: > > > > Yes, force_sig() unblocks and un-ignores the signal. However, unlike group-wide > > signals, thread-specific signals do not convert themselves to SIGKILL on delivery. > > The target thread should dequeue SIGSEGV and then it calls do_group_exit(). > > No it couldn't. > > Why? Because the target thread is the one that *caused* the SIGSEGV in the > first place. It's not going to dequeue *anything*. It's either going to > take the SIGSEGV, Hmm, can't understand. Yes, the target thread is the one that caused the SIGSEGV, it sends the signal to itself. entry.S:ret_from_exception should notice this signal and _dequeue_ it, no? This signal could be stealed by signal(SIG_IGN) which runs after it was delivered. > or it's going to get another SIGSEGV and now it's no > longer masked/handled and it's going to die. Yes sure. As I said, > and the target thread will take page fault again. My point was that it is _possible_ to steal a thread-local SIGSEGV even without signalfd, nothing bad should happen. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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