scsi: convert host_busy to atomic_t
Avoid taking the host-wide host_lock to check the per-host queue limit.
Instead we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Webb Scales <webbnh@hp.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Robert Elliott <elliott@hp.com>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 6200a26..21fb97b 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -600,7 +600,7 @@
if (level > 3)
scmd_printk(KERN_INFO, cmd,
"scsi host busy %d failed %d\n",
- cmd->device->host->host_busy,
+ atomic_read(&cmd->device->host->host_busy),
cmd->device->host->host_failed);
}
}