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Date: Sat, 15 Mar 2014 20:12:22 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: matt.helsley@...il.com, Andrew Morton <akpm@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Evgeniy Polyakov <zbr@...emap.net>, David Miller <davem@...emloft.net> Subject: Re: [PATCH] exit.c: call proc_exit_connector() after exit_state is set On 03/15, Linus Torvalds wrote: > > [ Going through old emails, adding relevant people, ie Oleg for > kernel/exit.c and David because he seems to be the go-to person for > connector issues judging by commits ] > > Patch looks sane to me, and logically that exit_connector thing would > pair with exit_notify(), but I'd like some comments on it. Please see the (confusing, my fault) discussion http://marc.info/?t=139327886600003 But in short, personally I agree with this change too. Just it was not clear from the changelog (to me ;) which problem this change actually tries to solve, because in general the task is not waitable after it reports PROC_EVENT_EXIT. So I think the patch is fine, but let me repeat: I hope that someone can confirm that netlink_broadcast() is safe even if release_task(current) was already called, so that the caller has no pids, sighand, is not visible via /proc/, etc. not that I expect this should not work, but still. > That > usability issue/race has been there since forever afaik. We probably > should never have added that process events connector thing, but since > we did and people apparently use it.. Yes... BTW, Guillaume, I forgot to mention that perhaps you can use signalfd(SIGCHLD) instead of connector, this is epoll-able too. SIGCHLD doesn't queue, so it can't tell you which child has exited, but WNOHANG should work. 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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