Date: Wed, 18 Sep 2013 22:40:32 +0400
From: Andrew Savchenko <bircoph@gmail.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        suspend-devel@lists.sourceforge.net
Subject: Re: [BUG] 3.7-rc regression bisected: s2disk fails to resume image:
 Processes could not be frozen, cannot continue resuming
Message-Id: <20130918224032.84e09e0c1372dbc51c86ab1e@gmail.com>
In-Reply-To: <20130918135239.GL13318@ZenIV.linux.org.uk>
References: <20130812234415.7db639bb0d664e56b6ab2ab2@gmail.com>
	<20130827074843.ba1b6f62cc0a6dca8e47c06c@gmail.com>
	<20130918135239.GL13318@ZenIV.linux.org.uk>
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Hello,

On Wed, 18 Sep 2013 14:52:39 +0100 Al Viro wrote:
> On Tue, Aug 27, 2013 at 07:48:43AM +0400, Andrew Savchenko wrote:
> > > Additional (but probably useless) information on this bug may be found
> > > here: https://forums.gentoo.org/viewtopic-p-7371120.html
>=20
> Something's very fishy there:
>=20
> [quote]
> Digging into suspend-utils code shows that the following ioctl fails on  =
   =20
> "/dev/snapshot":                                                         =
   =20
>                                                                          =
      =20
>                                     Code:                                =
      =20
>                           ioctl(dev, _IO(3, 1), 0);                      =
   =20
> [end quote]
>=20
> but that's _not_ anything freeze-related - that's HDIO_GETGEO, and with z=
ero
> as last argument it will fail, no matter what.  With EFAULT, if nothing
> else...
>=20
> Which ioctl() it really is?  A bit further down you write "I modified sus=
pend
> code to see errno, so freeze on /dev/snapshot fails [with EAGAIN]", so you
> have isolated the call in question.  Could you quote the actual code?

Actual code is from suspend-utils tree, swsusp.h:

static inline int freeze(int dev)
{
        return ioctl(dev, SNAPSHOT_FREEZE, 0);
}

And from suspend_ioctls.h:
#define SNAPSHOT_IOC_MAGIC      '3'
#define SNAPSHOT_FREEZE                 _IO(SNAPSHOT_IOC_MAGIC, 1)

My mistake, should be '3' instead of 3.

Best regards,
Andrew Savchenko

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