Commit 408aec3c authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

[S390] 3215: Remove tasklet. 



The 3215 console irq handler used to schedule a tasklet. However the
console irq handler also gets called from the infamous cio_tpi()
function. Which in turn does something like

local_bh_disable()
[call console irq handler]
_local_bh_enable()

_local_bh_enable() prevents execution of softirqs, which is intended
within cio_tpi(). However there might be a new softirq pending because
irq handler scheduled a tasklet.
In order to prevent this behaviour we just get rid of the tasklet.
It's not doing much anyway.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 2332ce1a

drivers/s390/char/con3215.c

+6 −20
Original line number Diff line number Diff line
@@ -89,7 +89,6 @@ struct raw3215_info { 
	int count;		      /* number of bytes in output buffer */

	int written;		      /* number of bytes in write requests */

	struct tty_struct *tty;	      /* pointer to tty structure if present */

	struct tasklet_struct tasklet;

	struct raw3215_req *queued_read; /* pointer to queued read requests */

	struct raw3215_req *queued_write;/* pointer to queued write requests */

	wait_queue_head_t empty_wait; /* wait queue for flushing */
@@ -342,21 +341,14 @@ raw3215_try_io(struct raw3215_info *raw) 
}



/*

 * The bottom half handler routine for 3215 devices. It tries to start

 * the next IO and wakes up processes waiting on the tty.

 * Try to start the next IO and wake up processes waiting on the tty.

 */

static void

raw3215_tasklet(void *data)

static void raw3215_next_io(struct raw3215_info *raw)

{

	struct raw3215_info *raw;

	struct tty_struct *tty;

	unsigned long flags;



	raw = (struct raw3215_info *) data;

	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);

	raw3215_mk_write_req(raw);

	raw3215_try_io(raw);

	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);

	tty = raw->tty;

	if (tty != NULL &&

	    RAW3215_BUFFER_SIZE - raw->count >= RAW3215_MIN_SPACE) {
@@ -381,7 +373,7 @@ raw3215_irq(struct ccw_device *cdev, unsigned long intparm, struct irb *irb) 
	cstat = irb->scsw.cmd.cstat;

	dstat = irb->scsw.cmd.dstat;

	if (cstat != 0)

		tasklet_schedule(&raw->tasklet);

		raw3215_next_io(raw);

	if (dstat & 0x01) { /* we got a unit exception */

		dstat &= ~0x01;	 /* we can ignore it */

	}
@@ -391,7 +383,7 @@ raw3215_irq(struct ccw_device *cdev, unsigned long intparm, struct irb *irb) 
			break;

		/* Attention interrupt, someone hit the enter key */

		raw3215_mk_read_req(raw);

		tasklet_schedule(&raw->tasklet);

		raw3215_next_io(raw);

		break;

	case 0x08:

	case 0x0C:
@@ -449,7 +441,7 @@ raw3215_irq(struct ccw_device *cdev, unsigned long intparm, struct irb *irb) 
		    raw->queued_read == NULL) {

			wake_up_interruptible(&raw->empty_wait);

		}

		tasklet_schedule(&raw->tasklet);

		raw3215_next_io(raw);

		break;

	default:

		/* Strange interrupt, I'll do my best to clean up */
@@ -461,7 +453,7 @@ raw3215_irq(struct ccw_device *cdev, unsigned long intparm, struct irb *irb) 
			raw->flags &= ~RAW3215_WORKING;

			raw3215_free_req(req);

		}

		tasklet_schedule(&raw->tasklet);

		raw3215_next_io(raw);

	}

	return;

}
@@ -675,9 +667,6 @@ raw3215_probe (struct ccw_device *cdev) 
		kfree(raw);

		return -ENOMEM;

	}

	tasklet_init(&raw->tasklet,

		     (void (*)(unsigned long)) raw3215_tasklet,

		     (unsigned long) raw);

	init_waitqueue_head(&raw->empty_wait);



	cdev->dev.driver_data = raw;
@@ -863,9 +852,6 @@ con3215_init(void) 
	cdev->handler = raw3215_irq;



	raw->flags |= RAW3215_FIXED;

	tasklet_init(&raw->tasklet,

		     (void (*)(unsigned long)) raw3215_tasklet,

		     (unsigned long) raw);

	init_waitqueue_head(&raw->empty_wait);



	/* Request the console irq */

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