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SubjectRe: autosuspend for SCSI devices
Hi!

> > > > > 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.

I guess you are right.

> /**
> * 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)


Hmm, scsi_block_when_ function, which does not _block_, and returns
inverted values from what would people expect.

...but this should fix it, no? [incremental to previous]
Pavel

diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index 3c184fe..7e5ea0d 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -10,6 +10,7 @@ #define DEBUG
#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
+#include <scsi/scsi_eh.h>

#include <linux/delay.h>

@@ -128,8 +129,11 @@ static int autosuspend_check(struct scsi
if (!(sdev->sdev_state == SDEV_RUNNING ||
sdev->sdev_state == SDEV_QUIESCE))
return -ENODEV;
+ if (!scsi_block_when_processing_errors(sdev))
+ return -EBUSY;

suspend_time = sdev->last_busy + sdev->autosuspend_delay;
+ /* FIXME: what if suspend_time - jiffies == -EPERM by some strange chance */
if (time_before(jiffies, suspend_time))
return suspend_time - jiffies;
return 0;
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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