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Date:   Wed, 5 Jun 2019 11:04:54 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Deepa Dinamani <deepa.kernel@gmail.com>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Davidlohr Bueso <dbueso@suse.de>, Jens Axboe <axboe@kernel.dk>,
        Davidlohr Bueso <dave@stgolabs.net>, e@80x24.org,
        Jason Baron <jbaron@akamai.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-aio@kvack.org, omar.kilani@gmail.com,
        Thomas Gleixner <tglx@linutronix.de>,
        stable <stable@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        David Laight <David.Laight@aculab.com>
Subject: Re: [PATCH] signal: remove the wrong signal_pending() check in
 restore_user_sigmask()
Message-ID: <20190605090453.GB32406@redhat.com>
References: <20190522032144.10995-1-deepa.kernel@gmail.com>
 <20190529161157.GA27659@redhat.com>
 <20190604134117.GA29963@redhat.com>
 <CAHk-=wjSOh5zmApq2qsNjmY-GMn4CWe9YwdcKPjT+nVoGiDKOQ@mail.gmail.com>
 <878sugewok.fsf@xmission.com>
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On 06/04, Eric W. Biederman wrote:
>
> >> -       restore_user_sigmask(ksig.sigmask, &sigsaved);
> >> -       if (signal_pending(current) && !ret)
> >> +
> >> +       interrupted = signal_pending(current);
> >> +       restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
> >> +       if (interrupted && !ret)
> >>                 ret = -ERESTARTNOHAND;
> >
> > are wrong to begin with, and we really should aim for an interface
> > which says "tell me whether you completed the system call, and I'll
> > give you an error return if not".
>
> The pattern you are pointing out is specific to io_pgetevents and it's
> variations.  It does look buggy to me but not for the reason you point
> out, but instead because it does not appear to let a pending signal
> cause io_pgetevents to return early.
>
> I suspect we should fix that and have do_io_getevents return
> -EINTR or -ERESTARTNOHAND like everyone else.

Exactly. It should not even check signal_pending(). It can rely on
wait_event_interruptible_hrtimeout().

> So can we please get this fix in and then look at cleaning up and
> simplifying this code.

Yes ;)

Oleg.