[S390] permanent subchannel busy conditions may cause I/O stall

In special conditions where a subchannel rejects the HALT I/O-
instruction with a busy indication (cc 2), I/O may stall.
I/O request termination logic retries HALT I/O indefinitely
because it expects HALT I/O to alter the subchannel status which
is not true when cc 2 is returned.
In case of a busy indication, try CLEAR I/O instruction immediately.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index ac6e0c7e43d9..7a39e0b0386c 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -152,7 +152,8 @@ ccw_device_cancel_halt_clear(struct ccw_device *cdev)
                 if (cdev->private->iretry) {
                         cdev->private->iretry--;
                         ret = cio_halt(sch);
-                        return (ret == 0) ? -EBUSY : ret;
+                        if (ret != -EBUSY)
+                                return (ret == 0) ? -EBUSY : ret;
                 }
                 /* halt io unsuccessful. */
                 cdev->private->iretry = 255;    /* 255 clear retries. */