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/con3270.c b/drivers/s390/char/con3270.c
index 4d7a9ba..6b1577c 100644 (file)
--- a/drivers/s390/char/con3270.c
+++ b/drivers/s390/char/con3270.c
@@ -400,7 +400,7 @@ con3270_deactivate(struct raw3270_view *view)
        del_timer(&cp->timer);
 }
 
-static int
+static void
 con3270_irq(struct con3270 *cp, struct raw3270_request *rq, struct irb *irb)
 {
        /* Handle ATTN. Schedule tasklet to read aid. */
@@ -418,7 +418,6 @@ con3270_irq(struct con3270 *cp, struct raw3270_request *rq, struct irb *irb)
                cp->update_flags = CON_UPDATE_ALL;
                con3270_set_timer(cp, 1);
        }
-       return RAW3270_IO_DONE;
 }
 
 /* Console view to a 3270 device. */

diff --git a/drivers/s390/char/fs3270.c b/drivers/s390/char/fs3270.c
index 71e9747..85eca1c 100644 (file)
--- a/drivers/s390/char/fs3270.c
+++ b/drivers/s390/char/fs3270.c
@@ -217,7 +217,7 @@ fs3270_deactivate(struct raw3270_view *view)
                fp->init->callback(fp->init, NULL);
 }
 
-static int
+static void
 fs3270_irq(struct fs3270 *fp, struct raw3270_request *rq, struct irb *irb)
 {
        /* Handle ATTN. Set indication and wake waiters for attention. */
@@ -233,7 +233,6 @@ fs3270_irq(struct fs3270 *fp, struct raw3270_request *rq, struct irb *irb)
                        /* Normal end. Copy residual count. */
                        rq->rescnt = irb->scsw.cmd.count;
        }
-       return RAW3270_IO_DONE;
 }
 
 /*

diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c
index 220acb4..0743f13 100644 (file)
--- a/drivers/s390/char/raw3270.c
+++ b/drivers/s390/char/raw3270.c
@@ -229,29 +229,6 @@ raw3270_request_set_idal(struct raw3270_request *rq, struct idal_buffer *ib)
 }
 
 /*
- * 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 @@ raw3270_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
        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 @@ raw3270_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
        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;
+               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);
+       }
 
-       switch (rc) {
-       case RAW3270_IO_DONE:
-               break;
-       case RAW3270_IO_BUSY:
-               /* 
-                * Intervention required by the operator. We have to wait
-                * for unsolicited device end.
-                */
+       if (test_bit(RAW3270_FLAGS_BUSY, &rp->flags))
+               /* Device busy, do not start I/O */
                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 (rq) {
                BUG_ON(list_empty(&rq->list));
                /* The request completed, remove from queue and do callback. */
@@ -408,6 +356,7 @@ raw3270_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
                /* 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 @@ raw3270_reset(struct raw3270_view *view)
        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 @@ raw3270_init_irq(struct raw3270_view *view, struct raw3270_request *rq,
                rp = view->dev;
                raw3270_read_modified(rp);
        }
-       return RAW3270_IO_DONE;
 }
 
 static struct raw3270_fn raw3270_init_fn = {

diff --git a/drivers/s390/char/raw3270.h b/drivers/s390/char/raw3270.h
index e1e41c2..56519cb 100644 (file)
--- a/drivers/s390/char/raw3270.h
+++ b/drivers/s390/char/raw3270.h
@@ -125,19 +125,13 @@ raw3270_request_final(struct raw3270_request *rq)
 
 void raw3270_buffer_address(struct raw3270 *, char *, unsigned short);
 
-/* Return value of *intv (see raw3270_fn below) can be one of the following: */
-#define RAW3270_IO_DONE                0       /* request finished */
-#define RAW3270_IO_BUSY                1       /* request still active */
-#define RAW3270_IO_RETRY       2       /* retry current request */
-#define RAW3270_IO_STOP                3       /* kill current request */
-
 /*
  * Functions of a 3270 view.
  */
 struct raw3270_fn {
        int  (*activate)(struct raw3270_view *);
        void (*deactivate)(struct raw3270_view *);
-       int  (*intv)(struct raw3270_view *,
+       void (*intv)(struct raw3270_view *,
                     struct raw3270_request *, struct irb *);
        void (*release)(struct raw3270_view *);
        void (*free)(struct raw3270_view *);

diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
index 54ea5a0..d6da186 100644 (file)
--- a/drivers/s390/char/tty3270.c
+++ b/drivers/s390/char/tty3270.c
@@ -645,7 +645,7 @@ tty3270_deactivate(struct raw3270_view *view)
        del_timer(&tp->timer);
 }
 
-static int
+static void
 tty3270_irq(struct tty3270 *tp, struct raw3270_request *rq, struct irb *irb)
 {
        /* Handle ATTN. Schedule tasklet to read aid. */
@@ -667,7 +667,6 @@ tty3270_irq(struct tty3270 *tp, struct raw3270_request *rq, struct irb *irb)
                tp->update_flags = TTY_UPDATE_ALL;
                tty3270_set_timer(tp, 1);
        }
-       return RAW3270_IO_DONE;
 }
 
 /*