[PATCH]SCSI:Do not block suspend for abandoned devices

[PATCH]SCSI:Do not block suspend for abandoned devices

[Oliver Neukum]

>From d0e0b88a5b271a45f00ab8ae9f22b992d5d090ba Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@neukum.org>
Date: Tue, 5 Oct 2010 17:06:46 +0200
Subject: [PATCH] SCSI:Do not block suspend for abandoned devices

If a device becomes inaccessible while a suspension
is carried out, the device is gone anyhow. There's
no need to block the suspension, as we'd ignore the
devices on later attempts anyway.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
---
 drivers/scsi/scsi_pm.c |   18 +++++++++++++++---
 1 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index d70e91a..396a60c 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -17,16 +17,28 @@
 static int scsi_dev_type_suspend(struct device *dev, pm_message_t msg)
 {
 	struct device_driver *drv;
-	int err;
+	struct scsi_device *sdev;
+	int err, state;
 
-	err = scsi_device_quiesce(to_scsi_device(dev));
+	sdev = to_scsi_device(dev);
+	err = scsi_device_quiesce(sdev);
 	if (err == 0) {
 		drv = dev->driver;
 		if (drv && drv->suspend)
 			err = drv->suspend(dev, msg);
 	}
 	dev_dbg(dev, "scsi suspend: %d\n", err);
-	return err;
+	
+	state = sdev->sdev_state;
+	switch (state) {
+	case SDEV_OFFLINE:
+	case SDEV_CANCEL:
+	case SDEV_DEL:
+		/* the device is dead, we can ignore the problem */
+		return 0;
+	default:
+		return err;
+	}
 }
 
 static int scsi_dev_type_resume(struct device *dev)
-- 
1.7.1

Re: [PATCH]SCSI:Do not block suspend for abandoned devices

[James Bottomley]

On Tue, 2010-10-05 at 17:21 +0200, Oliver Neukum wrote:
> From d0e0b88a5b271a45f00ab8ae9f22b992d5d090ba Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <oliver@neukum.org>
> Date: Tue, 5 Oct 2010 17:06:46 +0200
> Subject: [PATCH] SCSI:Do not block suspend for abandoned devices
> 
> If a device becomes inaccessible while a suspension
> is carried out, the device is gone anyhow. There's
> no need to block the suspension, as we'd ignore the
> devices on later attempts anyway.

So this clarifies what you're trying to do; thanks.  However, I still
think the premise is wrong: if we get a failure for any reason (whether
memory allocation or disk) we probably haven't flushed the disk cache
and our next action in suspend (whether to ram or disk) will power the
drive down and lose the cache data.  I really don't think blocking
suspend and informing the user is inappropriate here.

James

Re: [PATCH]SCSI:Do not block suspend for abandoned devices

[Oliver Neukum]

Am Dienstag, 5. Oktober 2010, 19:19:46 schrieb James Bottomley:
> On Tue, 2010-10-05 at 17:21 +0200, Oliver Neukum wrote:
> > From d0e0b88a5b271a45f00ab8ae9f22b992d5d090ba Mon Sep 17 00:00:00 2001
> > From: Oliver Neukum <oliver@neukum.org>
> > Date: Tue, 5 Oct 2010 17:06:46 +0200
> > Subject: [PATCH] SCSI:Do not block suspend for abandoned devices
> > 
> > If a device becomes inaccessible while a suspension
> > is carried out, the device is gone anyhow. There's
> > no need to block the suspension, as we'd ignore the
> > devices on later attempts anyway.
> 
> So this clarifies what you're trying to do; thanks.  However, I still
> think the premise is wrong: if we get a failure for any reason (whether
> memory allocation or disk) we probably haven't flushed the disk cache
> and our next action in suspend (whether to ram or disk) will power the
> drive down and lose the cache data.  I really don't think blocking
> suspend and informing the user is inappropriate here.

I see. It seems to me that this is true for SDEV_OFFLINE only.

	Regards
		Oliver