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

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Message-ID: <20070419150655.GC1481@korben.rdu.redhat.com>
Date:	Thu, 19 Apr 2007 11:06:56 -0400
From:	Josef Bacik <jwhiter@...hat.com>
To:	James Bottomley <James.Bottomley@...elEye.com>
Cc:	Josef Bacik <jwhiter@...hat.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, 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,

Josef 
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