From: David Laight <David.Laight@ACULAB.COM> To: "'Eric W. Biederman'" <ebiederm@xmission.com>, 'Oleg Nesterov' <oleg@redhat.com> Cc: '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: Tue, 11 Jun 2019 15:46:11 +0000 [thread overview] Message-ID: <05ffd0f434c64262aa767db81ad75ac1@AcuMS.aculab.com> (raw) In-Reply-To: <9199239a450d4ea397783ccf98742220@AcuMS.aculab.com> From: David Laight > Sent: 11 June 2019 10:52 ... > FWIW is ERESTARTNOHAND actually sane here? > If I've used setitimer() to get SIGALARM generated every second I'd > expect select() to return EINTR every second even if I don't > have a SIGALARM handler? Actually no - after sigset(SIGALRM, SIG_IGN) I'd expect absolutely nothing to happen when kill(pid, SIGALRM) is called. However if I run: struct itimerval itimerval = {{1, 0}, {1, 0}}; setitimer(ITIMER_REAL, &itimerval, NULL); sigset(SIGALRM, SIG_IGN); poll(0, 0, big_timeout); I see (with strace) poll() repeatedly returning ERESTART_RESTARTBLOCK and being restarted. Replacing poll() with pselect() returns ERESTARTNOHAND. (In both cases the timeout must be updated since the application does see the timeout.) I'm sure other unix kernels completely ignore signals set to SIG_IGN. So this restart dance just isn't needed. David - 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: "'Eric W. Biederman'" <ebiederm@xmission.com>, 'Oleg Nesterov' <oleg@redhat.com> Cc: '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: Tue, 11 Jun 2019 15:46:11 +0000 [thread overview] Message-ID: <05ffd0f434c64262aa767db81ad75ac1@AcuMS.aculab.com> (raw) In-Reply-To: <9199239a450d4ea397783ccf98742220@AcuMS.aculab.com> From: David Laight > Sent: 11 June 2019 10:52 ... > FWIW is ERESTARTNOHAND actually sane here? > If I've used setitimer() to get SIGALARM generated every second I'd > expect select() to return EINTR every second even if I don't > have a SIGALARM handler? Actually no - after sigset(SIGALRM, SIG_IGN) I'd expect absolutely nothing to happen when kill(pid, SIGALRM) is called. However if I run: struct itimerval itimerval = {{1, 0}, {1, 0}}; setitimer(ITIMER_REAL, &itimerval, NULL); sigset(SIGALRM, SIG_IGN); poll(0, 0, big_timeout); I see (with strace) poll() repeatedly returning ERESTART_RESTARTBLOCK and being restarted. Replacing poll() with pselect() returns ERESTARTNOHAND. (In both cases the timeout must be updated since the application does see the timeout.) I'm sure other unix kernels completely ignore signals set to SIG_IGN. So this restart dance just isn't needed. David - 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:[~2019-06-11 15:46 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 [this message] 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 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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