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From: Jamie Lokier <jamie@shareable.org>
To: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oren Laadan <orenl@cs.columbia.edu>,
	Matt Helsley <matthltc@us.ibm.com>,
	serue@us.ibm.com,
	Containers <containers@lists.linux-foundation.org>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC][PATCH 1/4][cr]: Add uid, euid params to f_modown()
Date: Wed, 12 May 2010 18:05:13 +0100	[thread overview]
Message-ID: <20100512170513.GD19314@shareable.org> (raw)
In-Reply-To: <1273617500-13653-2-git-send-email-sukadev@linux.vnet.ibm.com>

Sukadev Bhattiprolu wrote:
> Checkpoint/restart of file-owner.
> 
> Add uid, euid parameters to f_modown(). These parameters will be needed
> when restarting an application (and hence restoring the file information),
> from a checkpoint image.

This is used to make sure I/O signals on sockets, ttys, devices and so
on are delivered to a particular process.

If any of those signals are lost when an event happens around the same
time as c/r (for example, more data arriving on a pipe, a device
becomes readable/writable, or room becoming available to write, or
urgent data on a socket), a process depending on it can get stuck -
unless the process knows that c/r happened, so it knows to call
select() on all those fds after the c/r.

Can you say if the c/r avoids that kind of race condition?

Thanks,
-- Jamie

  reply	other threads:[~2010-05-12 17:05 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-11 22:38 [RFC][PATCH 0/4][cr]: Checkpoint/restart file-owner info Sukadev Bhattiprolu
2010-05-11 22:38 ` [RFC][PATCH 1/4][cr]: Add uid, euid params to f_modown() Sukadev Bhattiprolu
2010-05-12 17:05   ` Jamie Lokier [this message]
     [not found]     ` <20100512170513.GD19314-yetKDKU6eevNLxjTenLetw@public.gmane.org>
2010-05-12 17:30       ` Sukadev Bhattiprolu
2010-05-12 17:30     ` Sukadev Bhattiprolu
2010-05-12 20:12       ` Oren Laadan
     [not found]       ` <20100512173048.GC11144-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2010-05-12 20:12         ` Oren Laadan
     [not found]   ` <1273617500-13653-2-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2010-05-12 17:05     ` Jamie Lokier
     [not found] ` <1273617500-13653-1-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2010-05-11 22:38   ` Sukadev Bhattiprolu
2010-05-11 22:38   ` [RFC][PATCH 2/4][cr]: Define __f_setown_uid() Sukadev Bhattiprolu
2010-05-11 22:38   ` [RFC][PATCH 3/4][cr]: Checkpoint file-owner information Sukadev Bhattiprolu
2010-05-11 22:38   ` [RFC][PATCH 4/4][cr]: Restore file_owner info Sukadev Bhattiprolu
2010-05-11 22:38 ` [RFC][PATCH 2/4][cr]: Define __f_setown_uid() Sukadev Bhattiprolu
     [not found]   ` <1273617500-13653-3-git-send-email-sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2010-05-12  8:06     ` Serge E. Hallyn
     [not found]       ` <20100512080629.GB2636-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2010-05-12  8:43         ` Serge E. Hallyn
     [not found]           ` <20100512084317.GA8842-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2010-05-12 16:59             ` Sukadev Bhattiprolu
     [not found]               ` <20100512165922.GA11144-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2010-05-12 17:54                 ` Serge E. Hallyn
2010-05-12 14:07     ` Matthew Wilcox
2010-05-12 14:07   ` Matthew Wilcox
     [not found]     ` <20100512140741.GF10452-6jwH94ZQLHl74goWV3ctuw@public.gmane.org>
2010-05-12 17:05       ` Sukadev Bhattiprolu
2010-05-12 17:05     ` Sukadev Bhattiprolu
2010-05-11 22:38 ` [RFC][PATCH 3/4][cr]: Checkpoint file-owner information Sukadev Bhattiprolu
2010-05-11 22:38 ` [RFC][PATCH 4/4][cr]: Restore file_owner info Sukadev Bhattiprolu

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