Commit 8340ab60 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 2e63a3a6

drivers/s390/char/con3270.c

+1 −2
Original line number Diff line number Diff line
@@ -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. */

drivers/s390/char/fs3270.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

}



/*

drivers/s390/char/raw3270.c

+19 −82
Original line number Diff line number Diff line
@@ -228,29 +228,6 @@ raw3270_request_set_idal(struct raw3270_request *rq, struct idal_buffer *ib) 
	rq->ccw.flags |= CCW_FLAG_IDA;

}



/*

 * 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 = {

drivers/s390/char/raw3270.h

+1 −7
Original line number Diff line number Diff line
@@ -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 *);

drivers/s390/char/tty3270.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

}



/*

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