s390/3270: avoid endless I/O loop with disconnected 3270 terminals
If a 3270 terminal is disconnected while the tty view is active
the 3270 driver goes into an endless loop of failed I/O requests
until the terminal is connected again.
Add code to the raw3270 interrupt handler to check for unit checks
due to failed I/O requests and put the device to sleep with the
RAW3270_FLAGS_BUSY flag until a unsolicited device end interrupt
indicates that the device can be used again. while we are at it
simplify the 3270 irq handling and remove unnecessary code.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c
index 220acb4..0743f13 100644
--- a/drivers/s390/char/raw3270.c
+++ b/drivers/s390/char/raw3270.c
@@ -229,29 +229,6 @@
}
/*
- * Stop running ccw.
- */
-static int
-__raw3270_halt_io(struct raw3270 *rp, struct raw3270_request *rq)
-{
- int retries;
- int rc;
-
- if (raw3270_request_final(rq))
- return 0;
- /* Check if interrupt has already been processed */
- for (retries = 0; retries < 5; retries++) {
- if (retries < 2)
- rc = ccw_device_halt(rp->cdev, (long) rq);
- else
- rc = ccw_device_clear(rp->cdev, (long) rq);
- if (rc == 0)
- break; /* termination successful */
- }
- return rc;
-}
-
-/*
* Add the request to the request queue, try to start it if the
* 3270 device is idle. Return without waiting for end of i/o.
*/
@@ -342,7 +319,6 @@
struct raw3270 *rp;
struct raw3270_view *view;
struct raw3270_request *rq;
- int rc;
rp = dev_get_drvdata(&cdev->dev);
if (!rp)
@@ -350,55 +326,27 @@
rq = (struct raw3270_request *) intparm;
view = rq ? rq->view : rp->view;
- if (IS_ERR(irb))
- rc = RAW3270_IO_RETRY;
- else if (irb->scsw.cmd.fctl & SCSW_FCTL_HALT_FUNC) {
- rq->rc = -EIO;
- rc = RAW3270_IO_DONE;
- } else if (irb->scsw.cmd.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END |
- DEV_STAT_UNIT_EXCEP)) {
+ if (!IS_ERR(irb)) {
/* Handle CE-DE-UE and subsequent UDE */
- set_bit(RAW3270_FLAGS_BUSY, &rp->flags);
- rc = RAW3270_IO_BUSY;
- } else if (test_bit(RAW3270_FLAGS_BUSY, &rp->flags)) {
- /* Wait for UDE if busy flag is set. */
- if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) {
+ if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END)
clear_bit(RAW3270_FLAGS_BUSY, &rp->flags);
- /* Got it, now retry. */
- rc = RAW3270_IO_RETRY;
- } else
- rc = RAW3270_IO_BUSY;
- } else if (view)
- rc = view->fn->intv(view, rq, irb);
- else
- rc = RAW3270_IO_DONE;
-
- switch (rc) {
- case RAW3270_IO_DONE:
- break;
- case RAW3270_IO_BUSY:
- /*
- * Intervention required by the operator. We have to wait
- * for unsolicited device end.
- */
- return;
- case RAW3270_IO_RETRY:
- if (!rq)
- break;
- rq->rc = ccw_device_start(rp->cdev, &rq->ccw,
- (unsigned long) rq, 0, 0);
- if (rq->rc == 0)
- return; /* Successfully restarted. */
- break;
- case RAW3270_IO_STOP:
- if (!rq)
- break;
- __raw3270_halt_io(rp, rq);
- rq->rc = -EIO;
- break;
- default:
- BUG();
+ if (irb->scsw.cmd.dstat == (DEV_STAT_CHN_END |
+ DEV_STAT_DEV_END |
+ DEV_STAT_UNIT_EXCEP))
+ set_bit(RAW3270_FLAGS_BUSY, &rp->flags);
+ /* Handle disconnected devices */
+ if ((irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) &&
+ (irb->ecw[0] & SNS0_INTERVENTION_REQ))
+ set_bit(RAW3270_FLAGS_BUSY, &rp->flags);
+ /* Call interrupt handler of the view */
+ if (view)
+ view->fn->intv(view, rq, irb);
}
+
+ if (test_bit(RAW3270_FLAGS_BUSY, &rp->flags))
+ /* Device busy, do not start I/O */
+ return;
+
if (rq) {
BUG_ON(list_empty(&rq->list));
/* The request completed, remove from queue and do callback. */
@@ -408,6 +356,7 @@
/* Do put_device for get_device in raw3270_start. */
raw3270_put_view(view);
}
+
/*
* Try to start each request on request queue until one is
* started successful.
@@ -685,23 +634,12 @@
return rc;
}
-static int
+static void
raw3270_init_irq(struct raw3270_view *view, struct raw3270_request *rq,
struct irb *irb)
{
struct raw3270 *rp;
- /*
- * Unit-Check Processing:
- * Expect Command Reject or Intervention Required.
- */
- if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) {
- /* Request finished abnormally. */
- if (irb->ecw[0] & SNS0_INTERVENTION_REQ) {
- set_bit(RAW3270_FLAGS_BUSY, &view->dev->flags);
- return RAW3270_IO_BUSY;
- }
- }
if (rq) {
if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) {
if (irb->ecw[0] & SNS0_CMD_REJECT)
@@ -715,7 +653,6 @@
rp = view->dev;
raw3270_read_modified(rp);
}
- return RAW3270_IO_DONE;
}
static struct raw3270_fn raw3270_init_fn = {