Hi,
This needs to be copied to stable, added in cc.
Thanks,
~Saurav
>From: David Jeffery <djeffery@xxxxxxxxxx>
>
>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@xxxxxxxxxx>
>Signed-off-by: Chad Dupuis <chad.dupuis@xxxxxxxxxx>
>Cc: stable@xxxxxxxxxxxxxxx
>Signed-off-by: Saurav Kashyap <saurav.kashyap@xxxxxxxxxx>
>---
> drivers/scsi/qla2xxx/qla_os.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
>index d501bf5..a603967 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)) {
>--
>1.7.7
>
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