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authorDavid Jeffery <djeffery@redhat.com>2012-11-21 02:39:54 -0500
committerJames Bottomley <JBottomley@Parallels.com>2012-11-30 09:35:45 +0000
commita394aac88506159e047630fc90dc2242568382d8 (patch)
treed2ea22fb36af0b09a8f67d2f9d7a404ce68f0681 /drivers/scsi
parent63ea923a97cb0d78efcbbd229950e101588f0ddb (diff)
[SCSI] qla2xxx: Test and clear FCPORT_UPDATE_NEEDED atomically.
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> Cc: stable@vger.kernel.org Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/qla2xxx/qla_os.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index d501bf5f806..a60396725e8 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -4505,9 +4505,9 @@ 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)) {