From: Oliver Neukum <oneukum@suse.de>
Organization: Novell
To: Pavel Machek <pavel@suse.cz>
Subject: Re: autosuspend for SCSI devices
Date: Thu, 28 Aug 2008 23:17:37 +0200
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Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, linux-pm@lists.linux-foundation.org,
       James.Bottomley@hansenpartnership.com, linux-kernel@vger.kernel.org,
       teheo@novell.com, stefanr@s5r6.in-berlin.de, Martin.Leisner@xerox.com
References: <20080822105626.GA9475@elf.ucw.cz> <200808261301.45167.oneukum@suse.de> <20080828080427.GD15474@elf.ucw.cz>
In-Reply-To: <20080828080427.GD15474@elf.ucw.cz>
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Am Donnerstag 28 August 2008 10:04:27 schrieb Pavel Machek:
> On Tue 2008-08-26 13:01:43, Oliver Neukum wrote:
> > Am Dienstag 26 August 2008 11:43:55 schrieb Pavel Machek:
> > > > firstly, it doesn't consider error handling before suspending.
> > > 
> > > What problems do you see with error handling? This patch does not
> > > touch the error handling, and I do not think it needs to touch it.
> > 
> > You'd make scsi driver writers' life easier if you made sure no autosuspends
> > happen while they recover from errors. After all, you have no idea which
> > commands will get through while the bus is in disarray.
> 
> Well, they have to handle other commands while bus has problems,
> anyway, right? So I'm not creating any _new_ problems for them. 
> 
> 									Pavel


I am afraid this is not true.

	Regards
		Oliver
/**
 * scsi_block_when_processing_errors - Prevent cmds from being queued.
 * @sdev:	Device on which we are performing recovery.
 *
 * Description:
 *     We block until the host is out of error recovery, and then check to
 *     see whether the host or the device is offline.
 *
 * Return value:
 *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 */
int scsi_block_when_processing_errors(struct scsi_device *sdev)


/**
 * scsi_restart_operations - restart io operations to the specified host.
 * @shost:	Host we are restarting.
 *
 * Notes:
 *    When we entered the error handler, we blocked all further i/o to
 *    this device.  we need to 'reverse' this process.
 */
static void scsi_restart_operations(struct Scsi_Host *shost)
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