linux-kernel - Re: [RFC][PATCH] fix for async scsi scan sysfs problem (resend)

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Message-Id: <20070421002345.673d9988.akpm@linux-foundation.org>
Date:	Sat, 21 Apr 2007 00:23:45 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Josef Bacik <jwhiter@...hat.com>
Cc:	James Bottomley <James.Bottomley@...elEye.com>,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] fix for async scsi scan sysfs problem (resend)

On Thu, 19 Apr 2007 11:06:56 -0400 Josef Bacik <jwhiter@...hat.com> wrote:

> On Thu, Apr 19, 2007 at 10:02:36AM -0400, James Bottomley wrote:
> > On Thu, 2007-04-19 at 09:25 -0400, Josef Bacik wrote:
> > > Looking through everything I came to the conclusion that we don't really need
> > > the scsi_sysfs_add_devices in scsi_finish_async_scan, which gets run everytime
> > > we do a do_scan_async.  In doing the scanning, if we come upon anything we will
> > > already be registering the device with sysfs so the scsi_sysfs_add_devices step
> > > is kind of useless.
> > 
> > Unfortunately, it isn't.  The registration step while scanning is at the
> > end of scsi_add_lun():
> > 
> > 
> > 	if (!async && scsi_sysfs_add_sdev(sdev) != 0)
> > 		return SCSI_SCAN_NO_RESPONSE;
> > 
> > 	return SCSI_SCAN_LUN_PRESENT;
> > 
> > The !async should mean that the addition *only* occurs for the non async
> > scan case ... if you remove the post async scan add, we'll lose devices.
> > 
> > >   I tested this and it worked fine on my UP box (where the
> > > problem was happening) and my SMP box (where the problem wasn't happening).  Now
> > > I'm not entirely sure if this is correct, but I'm attaching the patch that I
> > > used to fix it for me, please point out if I've done something wrong or if there
> > > is a different way this needs to be fixed.  Thank you,
> > 
> > Could you add some debugging first to see if we're actually adding the
> > device twice (and also, if we are, what the value of the async is).
> >
> 
> Sorry I should have put that in the original post, I added debugging to
> kobject_add to check to see if we were adding something twice, thats how I
> figured out who was doing it
> 
> kobject rport-3:0-0: registering. parent: host3, set: devices
> kobject rport-3:0-0: registering. parent: fc_remote_ports, set: class_obj
> kobject target3:0:0: registering. parent: rport-3:0-0, set: devices
> kobject rport-3:0-1: registering. parent: host3, set: devices
> kobject rport-3:0-1: registering. parent: fc_remote_ports, set: class_obj
> kobject target3:0:0: registering. parent: fc_transport, set: class_obj
> kobject rport-3:0-2: registering. parent: host3, set: devices
> kobject rport-3:0-2: registering. parent: fc_remote_ports, set: class_obj
> kobject rport-3:0-3: registering. parent: host3, set: devices
> kobject rport-3:0-3: registering. parent: fc_remote_ports, set: class_obj
> kobject rport-3:0-4: registering. parent: host3, set: devices
> kobject rport-3:0-4: registering. parent: fc_remote_ports, set: class_obj
> kobject rport-3:0-5: registering. parent: host3, set: devices
> kobject rport-3:0-5: registering. parent: fc_remote_ports, set: class_obj
> kobject rport-3:0-6: registering. parent: host3, set: devices
> kobject rport-3:0-6: registering. parent: fc_remote_ports, set: class_obj
> kobject rport-3:0-7: registering. parent: host3, set: devices
> kobject rport-3:0-7: registering. parent: fc_remote_ports, set: class_obj
> >> kobject 3:0:0:0: registering. parent: target3:0:0, set: devices
> kobject 3:0:0:0: registering. parent: scsi_device, set: class_obj
> scsi 3:0:0:0: Direct-Access     IBM 1742-900         0520 PQ: 0 ANSI: 3
> >> kobject 3:0:0:0: registering. parent: target3:0:0, set: devices
> kobject_add failed for 3:0:0:0 with -EEXIST, don't try to register things with 
> the same name in the same directory.
> 
> Async in the first case is set and in the second case it isn't set.  Thank you,
> 

So.... do we now know what is causing this failure?
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