Commit 975f7d46 authored Dec 19, 2014 by Bruno Prémont Committed by Christoph Hellwig Jan 05, 2015

qla2xxx: fix busy wait regression



Commit e05fe292 (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>

parent 693a30b8

drivers/scsi/qla2xxx/qla_os.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -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;