3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: David Jeffery <[email protected]> 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 <[email protected]> Signed-off-by: Chad Dupuis <[email protected]> Signed-off-by: Saurav Kashyap <[email protected]> Signed-off-by: James Bottomley <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- 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 @@ -3541,9 +3541,9 @@ 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(ISP_QUIESCE_NEEDED, &base_vha->dpc_flags)) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
