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| author | Guenter Roeck <linux@roeck-us.net> | 2014-08-10 14:54:25 +0200 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2014-08-15 21:46:07 +0200 |
| commit | 045065d8a300a37218c548e9aa7becd581c6a0e8 (patch) | |
| tree | 61c4872d0174f3ef4671509f5088ce7a505cb3d0 /drivers/scsi | |
| parent | Merge tag 'pm+acpi-3.17-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff) | |
| download | linux-045065d8a300a37218c548e9aa7becd581c6a0e8.tar.xz linux-045065d8a300a37218c548e9aa7becd581c6a0e8.zip | |
[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>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 71e75c97f97a
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi')
| -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); } |