From: Oleg Nesterov <oleg@redhat.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Deepa Dinamani' <deepa.kernel@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Arnd Bergmann <arnd@arndb.de>, "dbueso@suse.de" <dbueso@suse.de>,
"axboe@kernel.dk" <axboe@kernel.dk>,
Davidlohr Bueso <dave@stgolabs.net>, Eric Wong <e@80x24.org>,
Jason Baron <jbaron@akamai.com>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
linux-aio <linux-aio@kvack.org>,
Omar Kilani <omar.kilani@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()
Date: Thu, 23 May 2019 18:36:04 +0200 [thread overview]
Message-ID: <20190523163604.GE23070@redhat.com> (raw)
In-Reply-To: <345cfba5edde470f9a68d913f44fa342@AcuMS.aculab.com>
On 05/23, David Laight wrote:
>
> From: Oleg Nesterov
> > On 05/23, David Laight wrote:
> > >
> > > I'm confused...
> >
> > Me too. To clarify, the current code is obviously buggy, pselect/whatever
> > shouldn't return 0 (or anything else) if it was interrupted and we are going
> > to deliver the signal.
>
> If it was interrupted the return value has to be EINTR.
Yes, and this is what we need to fix.
> Whether any signal handlers are called is a separate matter.
Not really... because in this case we know that the signal will be delivered,
> > Not sure I understand... OK, suppose that you do
> >
> > block-all-signals;
> > ret = pselect(..., sigmask(SIG_URG));
> >
> > if it returns success/timeout then the handler for SIG_URG should not be called?
>
> Ugg...
> Posix probably allows the signal handler be called at the point the event
> happens rather than being deferred until the system call completes.
> Queueing up the signal handler to be run at a later time (syscall exit)
> certainly makes sense.
> Definitely safest to call the signal handler even if success/timeout
> is returned.
Why?
> pselect() exists to stop the entry race, not the exit one.
pselect() has to block SIG_URG again before it returns to user-mode, right?
Suppose pselect() finds a ready fd, and this races with SIG_URG.
Why do you think the handler should run?
What if SIG_URG comes right after pselect() blocks SIG_URG again? I mean,
how this differs the case when it comes before, but a ready fd was already
found?
Oleg.
next prev parent reply other threads:[~2019-05-23 16:36 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 [this message]
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
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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