linux-kernel - Re: [CRIU] [PATCH 1/4] signalfd: add ability to return siginfo in a raw format

Open Source and information security mailing list archives

Message-ID: <20121226144751.GA18767@paralelels.com>
Date:	Wed, 26 Dec 2012 18:47:51 +0400
From:	Andrew Vagin <avagin@...allels.com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	Pavel Emelyanov <xemul@...allels.com>,
	David Howells <dhowells@...hat.com>,
	<linux-kernel@...r.kernel.org>, <criu@...nvz.org>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Andrey Wagin <avagin@...il.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	<linux-fsdevel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [CRIU] [PATCH 1/4] signalfd: add ability to return siginfo in a
 raw	format

On Tue, Dec 25, 2012 at 05:58:03PM +0100, Oleg Nesterov wrote:
> On 12/25, Pavel Emelyanov wrote:
> >
> > On 12/25/2012 07:27 PM, Oleg Nesterov wrote:
> > >
> > > I guess that probably you actually need DUMP, not DEQUEUE. but the
> > > latter is not trivial. However, perhaps we can do this assuming that
> > > all other threads are sleeping and nobody can do dequeue_signal().
> > > Say, we can play with ppos/llseek. If *ppos is not zero,
> > > signalfd_dequeue() could dump the nth entry from list or return 0.
> >
> > This would be perfect, but isn't it better to preserve the pos
> > semantics -- we do know size of entry we're about to copy, we can
> > treat pos as offset in bytes, not in elements.
> 
> nr-of-records looks better (more flexible) than nr-of-bytes to me. And
> perhaps we can also encode private-or-shared into ppos. But I will not
> argue in any case.

Oleg and Pavel, could you look at these two patches. I implemented in them,
what you described here.

> 
> Oleg.
> 
> _______________________________________________
> CRIU mailing list
> CRIU@...nvz.org
> http://lists.openvz.org/mailman/listinfo/criu

View attachment "0001-signal-add-helper-to-get-siginfo-without-removing-fr.patch" of type "text/plain" (1944 bytes)

View attachment "0002-signalfd-add-ability-to-get-signal-without-removing-.patch" of type "text/plain" (3411 bytes)

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