Messages in this thread | | | Date | Mon, 11 Aug 2014 08:16:23 +0200 | From | Hannes Reinecke <> | Subject | Re: [PATCH] scsi: Fix qemu boot hang problem |
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On 08/10/2014 02:54 PM, Guenter Roeck wrote: > The latest kernel fails to boot qemu arm images when using scsi > for disk access. Boot gets stuck after the following messages. > > brd: module loaded > sym53c8xx 0000:00:0c.0: enabling device (0100 -> 0103) > sym0: <895a> rev 0x0 at pci 0000:00:0c.0 irq 93 > sym0: No NVRAM, ID 7, Fast-40, LVD, parity checking > sym0: SCSI BUS has been reset. > scsi host0: sym-2.2.3 > > Bisect points to commit 71e75c97f97a ("scsi: convert device_busy to > atomic_t"). Code inspection shows the following suspicious change > in scsi_request_fn. > > out_delay: > - if (sdev->device_busy == 0 && !scsi_device_blocked(sdev)) > + if (atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev)) > blk_delay_queue(q, SCSI_QUEUE_DELAY); > } > > 'sdev->device_busy == 0' was replaced with 'atomic_read(&sdev->device_busy)', > meaning the logic was reversed. Changing this expression to > '!atomic_read(&sdev->device_busy)' fixes the problem. > > Cc: Christoph Hellwig <hch@lst.de> > Cc: Hannes Reinecke <hare@suse.de> > Cc: Webb Scales <webbnh@hp.com> > Cc: Jens Axboe <axboe@kernel.dk> > Signed-off-by: Guenter Roeck <linux@roeck-us.net> > --- > drivers/scsi/scsi_lib.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 9c44392..ce62e87 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1774,7 +1774,7 @@ static void scsi_request_fn(struct request_queue *q) > blk_requeue_request(q, req); > atomic_dec(&sdev->device_busy); > out_delay: > - if (atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev)) > + if (!atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev)) > blk_delay_queue(q, SCSI_QUEUE_DELAY); > } > > Reviewed-by: Hannes Reinecke <hare@suse.de>
Cheers,
Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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