Re: [PATCH 1/2] fix EH thread teardown

[Rolf Eike Beer <eike-kernel@sf-tec.de>]

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Christoph Hellwig wrote:
>As Rolf Eike Beer noted we might not actually get to the
>kthread_should_stop() because we are waiting in the semaphore forever.
>I didn't get a rmmod hang because of this, but my instrumentation showed
>the thread defitiyly didn't exit.
>
>So make sure to wake the EH thread before the kthread_stop, and to plug
>the reaming race check kthead_should_stop() a second time just before
>calling down_interruptible().
>
>
>Index: scsi-misc-2.6/drivers/scsi/hosts.c
>===================================================================
>--- scsi-misc-2.6.orig/drivers/scsi/hosts.c	2005-09-07 14:21:44.000000000
> +0200 +++ scsi-misc-2.6/drivers/scsi/hosts.c	2005-09-07 14:22:33.000000000
> +0200 @@ -226,8 +226,10 @@
> 	struct Scsi_Host *shost = dev_to_shost(dev);
> 	struct device *parent = dev->parent;
>
>-	if (shost->ehandler)
>+	if (shost->ehandler) {
>+		up(shost->eh_wait);
> 		kthread_stop(shost->ehandler);
>+	}
> 	if (shost->work_q)
> 		destroy_workqueue(shost->work_q);

Wouldn't this hang the same way if rescheduling happens between the up() and 
the kthread_stop()?

Eike

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