When all channel paths to a DASD device are lost and subsequently recovered, the path event handler starts one IO per path via dasd_sleep_on_immediatly() to execute read configuration data (RCD) with high priority. dasd_sleep_on_immediatly() works by terminating the currently running request before inserting the new request. If a concurrent caller, such as the attention handler dasd_eckd_check_attention_work() or the summary unit check handler summary_unit_check_handling_work(), also calls dasd_sleep_on_immediatly() while a path verification RCD is in progress, the RCD gets terminated. The problem is that a terminated request transitions from CLEARED to TERMINATED without going through the normal retry path in __dasd_device_process_ccw_queue. The RCD therefore returns -EIO, and the affected paths remain non-operational after recovery. RCD CQRs used for path verification already carry the DASD_CQR_VERIFY_PATH flag. Extend _dasd_term_running_cqr() to check this flag: instead of terminating such a request, return -EAGAIN. In dasd_sleep_on_immediatly(), loop on -EAGAIN with a short sleep, waiting for the path verification request to complete before inserting the new request. This is consistent with the already indefinite wait_event() that dasd_sleep_on_immediatly() uses for its own request, and all other callers (attention handler, summary unit check handler, reserve/release/steal-lock) benefit automatically without requiring changes. Reviewed-by: Jan Höppner Signed-off-by: Stefan Haberland --- drivers/s390/block/dasd.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 3181c06d91ce..d8d912a3b3fe 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -2511,6 +2512,13 @@ static inline int _dasd_term_running_cqr(struct dasd_device *device) if (list_empty(&device->ccw_queue)) return 0; cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist); + /* + * Path verification requests must not be terminated. They are critical + * for bringing paths back online. Terminating them would cause rc=-EIO + * because CLEARED requests skip the retry path. + */ + if (test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) + return -EAGAIN; rc = device->discipline->term_IO(cqr); if (!rc) /* @@ -2535,7 +2543,11 @@ int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr) return -EIO; } spin_lock_irq(get_ccwdev_lock(device->cdev)); - rc = _dasd_term_running_cqr(device); + while ((rc = _dasd_term_running_cqr(device)) == -EAGAIN) { + spin_unlock_irq(get_ccwdev_lock(device->cdev)); + msleep(1); + spin_lock_irq(get_ccwdev_lock(device->cdev)); + } if (rc) { spin_unlock_irq(get_ccwdev_lock(device->cdev)); return rc; -- 2.53.0