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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 13:33:23 -0800
commitf281233d3eba15fb225d21ae2e228fd4553d824a (patch)
tree51134454ba8acb558735f90be5540f7d756483e3 /drivers/scsi/scsi_error.c
parentbdbd01ac444bffb3c9aefed3059d12554059b320 (diff)
downloadop-kernel-dev-f281233d3eba15fb225d21ae2e228fd4553d824a.zip
op-kernel-dev-f281233d3eba15fb225d21ae2e228fd4553d824a.tar.gz
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/scsi_error.c')
-rw-r--r--drivers/scsi/scsi_error.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f3cf924..824b8fc 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -773,17 +773,15 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
struct Scsi_Host *shost = sdev->host;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft;
- unsigned long flags;
struct scsi_eh_save ses;
int rtn;
scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
shost->eh_action = &done;
- spin_lock_irqsave(shost->host_lock, flags);
scsi_log_send(scmd);
- shost->hostt->queuecommand(scmd, scsi_eh_done);
- spin_unlock_irqrestore(shost->host_lock, flags);
+ scmd->scsi_done = scsi_eh_done;
+ shost->hostt->queuecommand(shost, scmd);
timeleft = wait_for_completion_timeout(&done, timeout);
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