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authorChristoph Hellwig <hch@lst.de>2014-01-22 15:29:29 +0100
committerChristoph Hellwig <hch@lst.de>2014-07-25 07:43:43 -0400
commit74665016086615bbaa3fa6f83af410a0a4e029ee (patch)
tree9f9d8a692bec91dce69fd303eeedf16c35b41ac6 /drivers/scsi/qlogicpti.c
parent7ae65c0f9646c29432b69580b80e08632e6cd813 (diff)
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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>
Diffstat (limited to 'drivers/scsi/qlogicpti.c')
-rw-r--r--drivers/scsi/qlogicpti.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/qlogicpti.c b/drivers/scsi/qlogicpti.c
index 6d48d30bed05..740ae495aa77 100644
--- a/drivers/scsi/qlogicpti.c
+++ b/drivers/scsi/qlogicpti.c
@@ -959,7 +959,7 @@ static inline void update_can_queue(struct Scsi_Host *host, u_int in_ptr, u_int
/* Temporary workaround until bug is found and fixed (one bug has been found
already, but fixing it makes things even worse) -jj */
int num_free = QLOGICPTI_REQ_QUEUE_LEN - REQ_QUEUE_DEPTH(in_ptr, out_ptr) - 64;
- host->can_queue = host->host_busy + num_free;
+ host->can_queue = atomic_read(&host->host_busy) + num_free;
host->sg_tablesize = QLOGICPTI_MAX_SG(num_free);
}