linux-kernel - Re: [PATCH v2] signal: Adjust error codes according to restore_user

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Message-ID: <20190524145105.GD2655@redhat.com>
Date:   Fri, 24 May 2019 16:51:06 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Deepa Dinamani <deepa.kernel@...il.com>
Cc:     David Laight <David.Laight@...lab.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        "dbueso@...e.de" <dbueso@...e.de>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        Davidlohr Bueso <dave@...olabs.net>, Eric Wong <e@...24.org>,
        Jason Baron <jbaron@...mai.com>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        linux-aio <linux-aio@...ck.org>,
        Omar Kilani <omar.kilani@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2] signal: Adjust error codes according to
 restore_user_sigmask()

On 05/24, Deepa Dinamani wrote:
>
> I think you are misunderstanding what I said.

probably. Everything was very confusing to me from the very beginning.
And yes, I can hardly understand your emails, sorry. This one too :/

> You are taking things
> out of context. I was saying here what I did was inspired by why the
> syscall was designed to begin with.

which syscall?

> The syscall below refers to
> epoll_wait and not epoll_pwait.

So you tried to explain why epoll_pwait() was designed? Or what?

Either way, everything I said below still looks right to me. This probably
means that I still can't understand you.

But this is irrelevant. My main point is that the kernel was correct before
854a6ed568 ("signal: Add restore_user_sigmask()"), the (incomplete) patch I sent
tries to a) restore the correct behaviour and b) simplify/cleanup the code.

> On Fri, May 24, 2019 at 7:19 AM Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > On 05/23, Deepa Dinamani wrote:
> > >
> > > 1. block the signals you don't care about.
> > > 2. syscall()
> > > 3. unblock the signals blocked in 1.
> >
> > and even this part of your email is very confusing. because in this case
> > we can never miss a signal. I'd say
> >
> >         1. block the signals you don't care about
> >         2. unblock the signals which should interrupt the syscall below
> >         3. syscall()
> >         4. block the signals unblocked in 2.
> >
> > Oleg.
> >