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| author | Guenter Roeck <linux@roeck-us.net> | 2014-08-10 05:54:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-19 12:42:26 -0500 |
| commit | 480cadc2b7e0fa2bbab20141efb547dfe0c3707c (patch) | |
| tree | e5ca69de3a9f3e4ce8bddcb8bd4be00a87d32759 /drivers | |
| parent | 63d871cb0b9e4207044ced0322aa34d859fa463d (diff) | |
| download | linux-480cadc2b7e0fa2bbab20141efb547dfe0c3707c.tar.bz2 | |
scsi: Fix qemu boot hang problem
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.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Venkatesh Srinivas <venkateshs@google.com>
Reviewed-by: Webb Scales <webbnh@hp.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9c44392b748f..ce62e8798cc8 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); } |