From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk (man-pages)" Subject: Re: futex(2) man page update help request Date: Tue, 27 Jan 2015 08:48:28 +0100 Message-ID: <54C742CC.6030409@gmail.com> References: <537346E5.4050407@gmail.com> <5373D0CA.2050204@redhat.com> <54B7D87C.3090901@gmail.com> <1422037788.29655.0.camel@triegel.csb> <1422105142.29655.16.camel@triegel.csb> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1422105142.29655.16.camel-I2ZjUw8blINjztcc/or7kQ@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Torvald Riegel , Thomas Gleixner Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Carlos O'Donell , Darren Hart , Ingo Molnar , Jakub Jelinek , "linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , lkml , Arnd Bergmann , Steven Rostedt , Peter Zijlstra , Linux API , Darren Hart , Anton Blanchard , Eric Dumazet , bill o gallmeister , Jan Kiszka , Daniel Wagner , Rich Felker List-Id: linux-api@vger.kernel.org Hello Torvald, On 01/24/2015 02:12 PM, Torvald Riegel wrote: > On Sat, 2015-01-24 at 12:35 +0100, Thomas Gleixner wrote: >> So we should never see -EINTR in the case of a spurious wakeup here. >> >> But, here is the not so good news: >> >> I did some archaeology. The restart handling of futex_wait() got >> introduced in kernel 2.6.22, so anything older than that will have >> the spurious -EINTR issues. >> >> futex_wait_pi() always had the restart handling and glibc folks back >> then (2006) requested that it should never return -EINTR, so it >> unconditionally restarts the syscall whether a signal had been >> delivered or not. >> >> So kernels >= 2.6.22 should never return -EINTR spuriously. If that >> happens it's a bug and needs to be fixed. > > Thanks for looking into this. > > Michael, can you include the above in the documentation please? This is > useful for userspace code like glibc that expects a minimum kernel > version. Thanks! I've added some text to my draft to cover this point. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html