From 975f7d467480a11864d71a10dee908b83c5e682b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bruno=20Pr=C3=A9mont?= <bonbons@linux-vserver.org>
Date: Fri, 19 Dec 2014 10:29:16 +0100
Subject: [PATCH] qla2xxx: fix busy wait regression
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Commit e05fe29248 (qla2xxx: Honor FCP_RSP retry delay timer field.)
causes systems to busy-wait for about 3 minutes after boot prior to
detecting SAN disks.
During this wait period one kworker is running full-time
(though /proc/<pid>/stack has no useful data). Another kworker is
waiting for IO to complete during that whole time period.
Looking at drivers/scsi/qla2xxx/qla_os.c, fcport->retry_delay_timestamp
has a special value of 0 though that 0 value forces system to wait when
jiffies is very large value (e.g. 4294952605 - "negative" value when
signed on 32bit systems).
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Acked-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/scsi/qla2xxx/qla_os.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 12ca291c1380..cce1cbc1a927 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -734,7 +734,9 @@ qla2xxx_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
* Return target busy if we've received a non-zero retry_delay_timer
* in a FCP_RSP.
*/
- if (time_after(jiffies, fcport->retry_delay_timestamp))
+ if (fcport->retry_delay_timestamp == 0) {
+ /* retry delay not set */
+ } else if (time_after(jiffies, fcport->retry_delay_timestamp))
fcport->retry_delay_timestamp = 0;
else
goto qc24_target_busy;