| From a394aac88506159e047630fc90dc2242568382d8 Mon Sep 17 00:00:00 2001 |
| From: David Jeffery <djeffery@redhat.com> |
| Date: Wed, 21 Nov 2012 02:39:54 -0500 |
| Subject: SCSI: qla2xxx: Test and clear FCPORT_UPDATE_NEEDED atomically. |
| |
| 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/scsi/qla2xxx/qla_os.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/scsi/qla2xxx/qla_os.c |
| +++ b/drivers/scsi/qla2xxx/qla_os.c |
| @@ -3406,9 +3406,9 @@ qla2x00_do_dpc(void *data) |
| base_vha->host_no)); |
| } |
| |
| - 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(ISP_QUIESCE_NEEDED, &base_vha->dpc_flags)) { |
