s390/dasd: fix pathgroup race

If a new path is available we need to verify the path data. If it is the
first path for a device the stop bits are removed after path verification.
If a pathgroup is established we need to set system characteristics for
the lcu. Therefore I/O has to be started.
If the device is stopped the set system characteristics worker may block
the path verification worker and the device is blocked.

Turn on failfast for set system characteristics CQR to prevent a deadlock
with the path verification worker.

If a pathgroup is established on a device that is not in use trigger path
verification. Maybe we were not informed about a working path.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Reviewed-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 6498d15f874f..0595c763dafd 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -2157,6 +2157,7 @@ static int _dasd_sleep_on(struct dasd_ccw_req *maincqr, int interruptible)
                     test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
                     (!dasd_eer_enabled(device))) {
                         cqr->status = DASD_CQR_FAILED;
+                        cqr->intrc = -EAGAIN;
                         continue;
                 }
                 /* Don't try to start requests if device is stopped */
@@ -3270,6 +3271,16 @@ void dasd_generic_path_event(struct ccw_device *cdev, int *path_event)
                         dasd_schedule_device_bh(device);
                 }
                 if (path_event[chp] & PE_PATHGROUP_ESTABLISHED) {
+                        if (!(device->path_data.opm & eventlpm) &&
+                            !(device->path_data.tbvpm & eventlpm)) {
+                                /*
+                                 * we can not establish a pathgroup on an
+                                 * unavailable path, so trigger a path
+                                 * verification first
+                                 */
+                                device->path_data.tbvpm |= eventlpm;
+                                dasd_schedule_device_bh(device);
+                        }
                         DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                                       "Pathgroup re-established\n");
                         if (device->discipline->kick_validate)