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authorJeff Garzik <jeff@garzik.org>2010-11-16 02:10:29 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2010-11-16 16:33:23 -0500
commitf281233d3eba15fb225d21ae2e228fd4553d824a (patch)
tree51134454ba8acb558735f90be5540f7d756483e3 /drivers/scsi/megaraid/megaraid_sas.c
parentbdbd01ac444bffb3c9aefed3059d12554059b320 (diff)
SCSI host lock push-down
Move the mid-layer's ->queuecommand() invocation from being locked with the host lock to being unlocked to facilitate speeding up the critical path for drivers who don't need this lock taken anyway. The patch below presents a simple SCSI host lock push-down as an equivalent transformation. No locking or other behavior should change with this patch. All existing bugs and locking orders are preserved. Additionally, add one parameter to queuecommand, struct Scsi_Host * and remove one parameter from queuecommand, void (*done)(struct scsi_cmnd *) Scsi_Host* is a convenient pointer that most host drivers need anyway, and 'done' is redundant to struct scsi_cmnd->scsi_done. Minimal code disturbance was attempted with this change. Most drivers needed only two one-line modifications for their host lock push-down. Signed-off-by: Jeff Garzik <jgarzik@redhat.com> Acked-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/scsi/megaraid/megaraid_sas.c')
-rw-r--r--drivers/scsi/megaraid/megaraid_sas.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/scsi/megaraid/megaraid_sas.c b/drivers/scsi/megaraid/megaraid_sas.c
index eb29d5085131..7451bc096a01 100644
--- a/drivers/scsi/megaraid/megaraid_sas.c
+++ b/drivers/scsi/megaraid/megaraid_sas.c
@@ -1334,7 +1334,7 @@ megasas_dump_pending_frames(struct megasas_instance *instance)
1334 * @done: Callback entry point 1334 * @done: Callback entry point
1335 */ 1335 */
1336static int 1336static int
1337megasas_queue_command(struct scsi_cmnd *scmd, void (*done) (struct scsi_cmnd *)) 1337megasas_queue_command_lck(struct scsi_cmnd *scmd, void (*done) (struct scsi_cmnd *))
1338{ 1338{
1339 u32 frame_count; 1339 u32 frame_count;
1340 struct megasas_cmd *cmd; 1340 struct megasas_cmd *cmd;
@@ -1417,6 +1417,8 @@ megasas_queue_command(struct scsi_cmnd *scmd, void (*done) (struct scsi_cmnd *))
1417 return 0; 1417 return 0;
1418} 1418}
1419 1419
1420static DEF_SCSI_QCMD(megasas_queue_command)
1421
1420static struct megasas_instance *megasas_lookup_instance(u16 host_no) 1422static struct megasas_instance *megasas_lookup_instance(u16 host_no)
1421{ 1423{
1422 int i; 1424 int i;