lkml.org 
[lkml]   [2013]   [Jan]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 064/222] qla2xxx: Test and clear FCPORT_UPDATE_NEEDED atomically.
Date
3.5.7.3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Jeffery <djeffery@redhat.com>

commit a394aac88506159e047630fc90dc2242568382d8 upstream.

When the qla2xxx driver loses access to multiple, remote ports, there is a race
condition which can occur which will keep the request stuck on a scsi request
queue indefinitely.

This bad state occurred do to a race condition with how the FCPORT_UPDATE_NEEDED
bit is set in qla2x00_schedule_rport_del(), and how it is cleared in
qla2x00_do_dpc(). The problem port has its drport pointer set, but it has never
been processed by the driver to inform the fc transport that the port has been
lost. qla2x00_schedule_rport_del() sets drport, and then sets the
FCPORT_UPDATE_NEEDED bit. In qla2x00_do_dpc(), the port lists are walked and
any drport pointer is handled and the fc transport informed of the port loss,
then the FCPORT_UPDATE_NEEDED bit is cleared. This leaves a race where the
dpc thread is processing one port removal, another port removal is marked
with a call to qla2x00_schedule_rport_del(), and the dpc thread clears the
bit for both removals, even though only the first removal was actually
handled. Until another event occurs to set FCPORT_UPDATE_NEEDED, the later
port removal is never finished and qla2xxx stays in a bad state which causes
requests to become stuck on request queues.

This patch updates the driver to test and clear FCPORT_UPDATE_NEEDED
atomically. This ensures the port state changes are processed and not lost.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
drivers/scsi/qla2xxx/qla_os.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 6d1d873..f6f555a 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -3801,9 +3801,9 @@ qla2x00_do_dpc(void *data)
"ISP abort end.\n");
}

- if (test_bit(FCPORT_UPDATE_NEEDED, &base_vha->dpc_flags)) {
+ if (test_and_clear_bit(FCPORT_UPDATE_NEEDED,
+ &base_vha->dpc_flags)) {
qla2x00_update_fcports(base_vha);
- clear_bit(FCPORT_UPDATE_NEEDED, &base_vha->dpc_flags);
}

if (test_bit(SCR_PENDING, &base_vha->dpc_flags)) {
--
1.7.9.5


\
 
 \ /
  Last update: 2013-01-16 18:43    [W:0.999 / U:0.524 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site