Re: [Patch] Fix oops on rmmod usb-storage

[Hannes Reinecke <hare@suse.de>]

Christoph Hellwig wrote:
> [please send scsi issues to linux-scsi, thanks]
> 
> 
>>It turned out that in drivers/scsi/hosts.c:scsi_remove_host()
>>first the host is removed with scsi_forget_host() and _then_ all 
>>outstanding I/O to this host is cancelled with scsi_host_cancel(). 
>>Sounds a bit fishy as scsi_host_cancel() tries to talk to a host which 
>>we just have deleted ...
>>(Incidentally, this is most likely the same bug as Bug #2752 and #3480 
>>from bugme.osdl.org :-).
>>(And also #133249 from bugzilla.redhat.com :-).
>>
>>The attached patch corrects this.
>>Please apply.
> 
> 
> I'ts not that easy.  If we cancel the host first we won't get our write
> caches flushed because the drivers don't accept the SYNCRHONIZE_CACHE.
> command in cancelled state.  Mike just changed the order to what it is
> now a short while ago.
> 
Yeah, Jens Axboe just pointed that out.

> So we'll have to find a way to send a SYNCHRNOZIE_CACHE command even
> in canncelled state.
> 
> In fact I can't see how these problems could happen, and that they only
> happen with usb-storage seems strange.
Well, the thing is: When usb-storage calls scsi_remove_host() the device 
is already gone; whether or not we can synchronize the cache is a moot 
point there.

And if I understood the comment to the Changeset properly, the patch was 
just to remove the 'Synchronizing SCSI cache' message.
I can live with that. Kernel Oops is much worse.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SuSE Linux AG				S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html