From: David Laight <David.Laight@ACULAB.COM> To: 'Oleg Nesterov' <oleg@redhat.com> Cc: "'Eric W. Biederman'" <ebiederm@xmission.com>, 'Andrew Morton' <akpm@linux-foundation.org>, 'Deepa Dinamani' <deepa.kernel@gmail.com>, "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>, "'arnd@arndb.de'" <arnd@arndb.de>, "'dbueso@suse.de'" <dbueso@suse.de>, "'axboe@kernel.dk'" <axboe@kernel.dk>, "'dave@stgolabs.net'" <dave@stgolabs.net>, "'e@80x24.org'" <e@80x24.org>, "'jbaron@akamai.com'" <jbaron@akamai.com>, "'linux-fsdevel@vger.kernel.org'" <linux-fsdevel@vger.kernel.org>, "'linux-aio@kvack.org'" <linux-aio@kvack.org>, "'omar.kilani@gmail.com'" <omar.kilani@gmail.com>, "'tglx@linutronix.de'" <tglx@linutronix.de>, 'Al Viro' <viro@ZenIV.linux.org.uk>, 'Linus Torvalds' <torvalds@linux-foundation.org>, "'linux-arch@vger.kernel.org'" <linux-arch@vger.kernel.org> Subject: RE: [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask Date: Thu, 13 Jun 2019 10:56:17 +0000 [thread overview] Message-ID: <66311ce9762849f7988c16bc752ea5a9@AcuMS.aculab.com> (raw) In-Reply-To: <20190613094324.GA12506@redhat.com> From: Oleg Nesterov > Sent: 13 June 2019 10:43 > On 06/13, David Laight wrote: > > > > I tested NetBSD last night. > > pselect() always calls the signal handlers even when an fd is ready. > > I'm beginning to suspect that this is the 'standards conforming' behaviour. > > May be. May be not. I have no idea. > > > > The ToG page for pselect() http://pubs.opengroup.org/onlinepubs/9699919799/functions/pselect.html > > > says: > > > "If sigmask is not a null pointer, then the pselect() function shall replace > > > the signal mask of the caller by the set of signals pointed to by sigmask > > > before examining the descriptors, and shall restore the signal mask of the > > > calling thread before returning." > > > > Note that it says 'before examining the descriptors' not 'before blocking'. > > And you interpret this as if a pending signal should be delivered in any case, > even if pselect succeeds. Again, perhaps you are right, but to me this is simply > undocumented. This text (from http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html) is moderately clear: ... if all threads within the process block delivery of the signal, the signal shall remain pending on the process until a thread calls a sigwait() function selecting that signal, a thread unblocks delivery of the signal, or the action associated with the signal is set to ignore the signal. So when pselect() 'replaces the signal mask' any pending signals should be delivered. And 'delivery' means 'call the signal handler'. All Unix systems will defer calling the signal handler until the system call returns, but this is not mandated by Posix. > However, linux never did this. Until the commit 854a6ed56839 ("signal: Add > restore_user_sigmask()"). This commit caused regression. We had to revert it. That change wasn't expected to change the behaviour... David > > > If nothing else the man pages need a note about the standards and portability. > > Agreed. > > Oleg. - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM> To: 'Oleg Nesterov' <oleg@redhat.com> Cc: "'Eric W. Biederman'" <ebiederm@xmission.com>, 'Andrew Morton' <akpm@linux-foundation.org>, 'Deepa Dinamani' <deepa.kernel@gmail.com>, "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>, "'arnd@arndb.de'" <arnd@arndb.de>, "'dbueso@suse.de'" <dbueso@suse.de>, "'axboe@kernel.dk'" <axboe@kernel.dk>, "'dave@stgolabs.net'" <dave@stgolabs.net>, "'e@80x24.org'" <e@80x24.org>, "'jbaron@akamai.com'" <jbaron@akamai.com>, "'linux-fsdevel@vger.kernel.org'" <linux-fsdevel@vger.kernel.org>, "'linux-aio@kvack.org'" <linux-aio@kvack.org>, "'omar.kilani@gmail.com'" <omar.kilani@gmail.com>, "'tglx@linutronix.de'" <tglx@linutronix.de>, 'Al Viro' <viro@ZenIV.linux.org.uk>, 'Linus Torvalds' <torvalds@linux-foundation.org>, "'linux-arch@vger.kernel.org'" <linux-arch@vger.kernel.org> Subject: RE: [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask Date: Thu, 13 Jun 2019 10:56:17 +0000 [thread overview] Message-ID: <66311ce9762849f7988c16bc752ea5a9@AcuMS.aculab.com> (raw) In-Reply-To: <20190613094324.GA12506@redhat.com> From: Oleg Nesterov > Sent: 13 June 2019 10:43 > On 06/13, David Laight wrote: > > > > I tested NetBSD last night. > > pselect() always calls the signal handlers even when an fd is ready. > > I'm beginning to suspect that this is the 'standards conforming' behaviour. > > May be. May be not. I have no idea. > > > > The ToG page for pselect() http://pubs.opengroup.org/onlinepubs/9699919799/functions/pselect.html > > > says: > > > "If sigmask is not a null pointer, then the pselect() function shall replace > > > the signal mask of the caller by the set of signals pointed to by sigmask > > > before examining the descriptors, and shall restore the signal mask of the > > > calling thread before returning." > > > > Note that it says 'before examining the descriptors' not 'before blocking'. > > And you interpret this as if a pending signal should be delivered in any case, > even if pselect succeeds. Again, perhaps you are right, but to me this is simply > undocumented. This text (from http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html) is moderately clear: ... if all threads within the process block delivery of the signal, the signal shall remain pending on the process until a thread calls a sigwait() function selecting that signal, a thread unblocks delivery of the signal, or the action associated with the signal is set to ignore the signal. So when pselect() 'replaces the signal mask' any pending signals should be delivered. And 'delivery' means 'call the signal handler'. All Unix systems will defer calling the signal handler until the system call returns, but this is not mandated by Posix. > However, linux never did this. Until the commit 854a6ed56839 ("signal: Add > restore_user_sigmask()"). This commit caused regression. We had to revert it. That change wasn't expected to change the behaviour... David > > > If nothing else the man pages need a note about the standards and portability. > > Agreed. > > Oleg. - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: <a href=mailto:"aart@kvack.org">aart@kvack.org</a>
next prev parent reply other threads:[~2019-06-13 15:32 UTC|newest] Thread overview: 155+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-22 3:21 [PATCH v2] signal: Adjust error codes according to restore_user_sigmask() Deepa Dinamani 2019-05-22 15:05 ` Oleg Nesterov 2019-05-22 15:55 ` Deepa Dinamani 2019-05-22 16:14 ` Oleg Nesterov 2019-05-22 16:33 ` Deepa Dinamani 2019-05-23 9:03 ` David Laight 2019-05-23 14:59 ` Oleg Nesterov 2019-05-23 16:18 ` David Laight 2019-05-23 16:36 ` Oleg Nesterov 2019-05-23 16:56 ` David Laight 2019-05-23 18:06 ` Deepa Dinamani 2019-05-23 20:41 ` Deepa Dinamani 2019-05-23 21:06 ` Deepa Dinamani 2019-05-24 9:58 ` David Laight 2019-05-24 14:10 ` Oleg Nesterov 2019-05-24 15:16 ` Deepa Dinamani 2019-05-24 16:33 ` Oleg Nesterov 2019-05-24 17:01 ` Deepa Dinamani 2019-05-27 15:04 ` Oleg Nesterov 2019-05-28 20:47 ` Deepa Dinamani 2019-05-29 16:57 ` Oleg Nesterov 2019-05-29 18:42 ` Deepa Dinamani 2019-05-28 9:02 ` David Laight 2019-05-28 9:12 ` David Laight 2019-05-28 11:37 ` Deepa Dinamani 2019-05-28 12:04 ` David Laight 2019-05-24 14:19 ` Oleg Nesterov 2019-05-24 14:29 ` Deepa Dinamani 2019-05-24 14:51 ` Oleg Nesterov 2019-05-24 13:29 ` Oleg Nesterov 2019-05-24 14:59 ` David Laight 2019-05-24 15:09 ` David Laight 2019-05-24 15:46 ` Oleg Nesterov 2019-05-24 15:44 ` Oleg Nesterov 2019-05-24 16:40 ` David Laight 2019-05-23 14:33 ` Oleg Nesterov 2019-05-22 22:18 ` Chris Down 2019-05-22 22:52 ` Deepa Dinamani 2019-05-22 22:52 ` Deepa Dinamani 2019-05-29 16:11 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Oleg Nesterov 2019-05-29 16:54 ` David Laight 2019-05-29 18:50 ` Eric Wong 2019-05-30 9:34 ` David Laight 2019-05-30 13:04 ` pselect/etc semantics Eric W. Biederman 2019-05-29 16:56 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Deepa Dinamani 2019-05-29 18:26 ` Deepa Dinamani 2019-05-29 22:32 ` Arnd Bergmann 2019-05-30 1:54 ` pselect/etc semantics Eric W. Biederman 2019-05-30 18:28 ` Arnd Bergmann 2019-05-30 14:40 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Oleg Nesterov 2019-05-30 18:37 ` Arnd Bergmann 2019-05-30 13:01 ` pselect/etc semantics Eric W. Biederman 2019-05-30 15:18 ` David Laight 2019-05-30 16:13 ` Oleg Nesterov 2019-05-30 15:38 ` Eric W. Biederman 2019-05-30 15:48 ` Deepa Dinamani 2019-05-30 16:59 ` Deepa Dinamani 2019-05-30 16:08 ` Oleg Nesterov 2019-05-30 17:20 ` Eric W. Biederman 2019-05-30 16:22 ` David Laight 2019-05-30 15:57 ` Oleg Nesterov 2019-05-30 21:03 ` Eric Wong 2019-06-04 13:41 ` [PATCH] signal: remove the wrong signal_pending() check in restore_user_sigmask() Oleg Nesterov 2019-06-04 15:31 ` Eric W. Biederman 2019-06-04 15:31 ` Eric W. Biederman 2019-06-04 15:57 ` David Laight 2019-06-04 15:57 ` David Laight 2019-06-04 16:37 ` Arnd Bergmann 2019-06-04 18:14 ` Deepa Dinamani 2019-06-04 18:35 ` Eric Wong 2019-06-04 21:26 ` Linus Torvalds 2019-06-04 22:24 ` Eric Wong 2019-06-04 23:51 ` Eric W. Biederman 2019-06-05 9:04 ` Oleg Nesterov 2019-06-05 8:56 ` Oleg Nesterov 2019-06-05 9:02 ` David Laight 2019-06-05 9:25 ` Oleg Nesterov 2019-06-05 9:58 ` David Laight 2019-06-05 15:58 ` [PATCH -mm 0/1] signal: simplify set_user_sigmask/restore_user_sigmask Oleg Nesterov 2019-06-05 15:58 ` [PATCH -mm 1/1] " Oleg Nesterov 2019-06-06 0:14 ` kbuild test robot 2019-06-06 1:06 ` kbuild test robot 2019-06-06 7:25 ` Oleg Nesterov 2019-06-06 7:30 ` Sedat Dilek 2019-06-05 17:24 ` [PATCH -mm 0/1] " Linus Torvalds 2019-06-06 9:05 ` David Laight 2019-06-06 11:05 ` Oleg Nesterov 2019-06-06 11:29 ` David Laight 2019-06-06 12:41 ` Oleg Nesterov 2019-06-06 13:23 ` David Laight 2019-06-06 10:22 ` Oleg Nesterov 2019-06-06 11:32 ` [PATCH -mm V2 1/1] " Oleg Nesterov 2019-06-06 14:08 ` [PATCH 0/2] select: simplify the usage of restore_saved_sigmask_unless() Oleg Nesterov 2019-06-06 14:08 ` [PATCH 1/2] select: change do_poll() to return -ERESTARTNOHAND rather than -EINTR Oleg Nesterov 2019-06-07 18:05 ` Linus Torvalds 2019-06-06 14:09 ` [PATCH 2/2] select: shift restore_saved_sigmask_unless() into poll_select_copy_remaining() Oleg Nesterov 2019-06-07 21:39 ` [RFC PATCH 0/5]: Removing saved_sigmask Eric W. Biederman 2019-06-07 21:39 ` Eric W. Biederman 2019-06-07 21:41 ` [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask Eric W. Biederman 2019-06-07 21:41 ` Eric W. Biederman 2019-06-07 21:41 ` Eric W. Biederman 2019-06-07 22:07 ` Linus Torvalds 2019-06-07 22:07 ` Linus Torvalds 2019-06-10 16:22 ` Oleg Nesterov 2019-06-10 21:20 ` Eric W. Biederman 2019-06-11 9:52 ` David Laight 2019-06-11 11:14 ` David Laight 2019-06-12 12:55 ` Eric W. Biederman 2019-06-12 12:55 ` Eric W. Biederman 2019-06-12 12:55 ` Eric W. Biederman 2019-06-12 13:24 ` David Laight 2019-06-12 13:24 ` David Laight 2019-06-12 13:35 ` Oleg Nesterov 2019-06-12 13:35 ` Oleg Nesterov 2019-06-12 13:39 ` David Laight 2019-06-12 13:39 ` David Laight 2019-06-11 15:46 ` David Laight 2019-06-11 15:46 ` David Laight 2019-06-12 12:40 ` Eric W. Biederman 2019-06-12 12:40 ` Eric W. Biederman 2019-06-12 12:40 ` Eric W. Biederman 2019-06-12 13:45 ` Oleg Nesterov 2019-06-12 14:18 ` David Laight 2019-06-12 15:11 ` Eric W. Biederman 2019-06-12 15:11 ` Eric W. Biederman 2019-06-12 15:37 ` Oleg Nesterov 2019-06-12 15:37 ` Oleg Nesterov 2019-06-13 8:48 ` David Laight 2019-06-13 8:48 ` David Laight 2019-06-13 9:43 ` Oleg Nesterov 2019-06-13 9:43 ` Oleg Nesterov 2019-06-13 10:56 ` David Laight [this message] 2019-06-13 10:56 ` David Laight 2019-06-13 12:43 ` Oleg Nesterov 2019-06-13 12:43 ` Oleg Nesterov 2019-06-11 18:55 ` Oleg Nesterov 2019-06-11 19:02 ` Eric W. Biederman 2019-06-11 19:02 ` Eric W. Biederman 2019-06-12 8:39 ` David Laight 2019-06-12 13:09 ` Eric W. Biederman 2019-06-12 13:09 ` Eric W. Biederman 2019-06-12 13:09 ` Eric W. Biederman 2019-06-07 21:41 ` [RFC PATCH 2/5] signal/kvm: Stop using sigprocmask in kvm_sigset_(activate|deactivate) Eric W. Biederman 2019-06-07 21:41 ` Eric W. Biederman 2019-06-07 21:41 ` Eric W. Biederman 2019-06-07 21:42 ` [RFC PATCH 3/5] signal: Always keep real_blocked in sync with blocked Eric W. Biederman 2019-06-07 21:42 ` Eric W. Biederman 2019-06-07 21:42 ` Eric W. Biederman 2019-06-07 21:43 ` [RFC PATCH 4/5] signal: Remove saved_sigmask Eric W. Biederman 2019-06-07 21:43 ` Eric W. Biederman 2019-06-07 21:43 ` Eric W. Biederman 2019-06-07 21:44 ` [RFC PATCH 5/5] signal: Remove the unnecessary restore_sigmask flag Eric W. Biederman 2019-06-07 21:44 ` Eric W. Biederman 2019-06-07 21:44 ` Eric W. Biederman 2019-06-11 18:58 ` [RFC PATCH 0/5]: Removing saved_sigmask Oleg Nesterov
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