From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 6/7] fcntl: Don't use ambiguous SIG_POLL si_codes
Date: Thu, 20 Jul 2017 18:16:04 +0200
Message-ID: <20170720161603.GA14430@redhat.com>
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	<20170718140651.15973-6-ebiederm@xmission.com>
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To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrei Vagin <avagin-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>, Greg KH <greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>, Linux Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, Pavel Emelyanov <xemul-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Cyrill Gorcunov <gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>, Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Willy Tarreau <w@1wt.eu>, Andrey Vagin <avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
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On 07/18, Eric W. Biederman wrote:
>
> -			BUG_ON((reason & __SI_MASK) != __SI_POLL);
> +			BUG_ON((reason < POLL_IN) || (reason > NSIGPOLL));
                                                      ^^^^^^^^^^^^^^^^^
looks obviously wrong? Say, POLL_IN is obviously > NSIGPOLL == 6.

Probably you meant

			BUG_ON((reason < POLL_IN) || (reason - POLL_IN > NSIGPOLL)

?

but this contradicts with the next line:

>  			if (reason - POLL_IN >= NSIGPOLL)
>  				si.si_band  = ~0L;

confused...

Oleg.

From mboxrd@z Thu Jan  1 00:00:00 1970
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        Thu, 20 Jul 2017 12:16:08 -0400
Date: Thu, 20 Jul 2017 18:16:04 +0200
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 6/7] fcntl: Don't use ambiguous SIG_POLL si_codes
Message-ID: <20170720161603.GA14430@redhat.com>
References: <87o9shg7t7.fsf_-_@xmission.com>
 <20170718140651.15973-6-ebiederm@xmission.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Al Viro <viro@zeniv.linux.org.uk>, Andrei Vagin <avagin@virtuozzo.com>, Thomas Gleixner <tglx@linutronix.de>, Greg KH <greg@kroah.com>, Andrey Vagin <avagin@openvz.org>, Serge Hallyn <serge@hallyn.com>, Pavel Emelyanov <xemul@virtuozzo.com>, Cyrill Gorcunov <gorcunov@openvz.org>, Peter Zijlstra <peterz@infradead.org>, Willy Tarreau <w@1wt.eu>, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Linux Containers <containers@lists.linux-foundation.org>, Michael Kerrisk <mtk.manpages@gmail.com>
Message-ID: <20170720161604.PiWz-tlx8ZVfRK7k3gCbR2HNRCVK_K_-oXBWYidSkWQ@z>

On 07/18, Eric W. Biederman wrote:
>
> -			BUG_ON((reason & __SI_MASK) != __SI_POLL);
> +			BUG_ON((reason < POLL_IN) || (reason > NSIGPOLL));
                                                      ^^^^^^^^^^^^^^^^^
looks obviously wrong? Say, POLL_IN is obviously > NSIGPOLL == 6.

Probably you meant

			BUG_ON((reason < POLL_IN) || (reason - POLL_IN > NSIGPOLL)

?

but this contradicts with the next line:

>  			if (reason - POLL_IN >= NSIGPOLL)
>  				si.si_band  = ~0L;

confused...

Oleg.