From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Fri, 10 Oct 2008 19:33:28 +0000 (+0200)
Subject: [S390] 3215: Remove tasklet.
X-Git-Tag: v2.6.28-rc1~721^2~2
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=408aec3c6c3cb5b4774f96ea7a35cd15ee91a56f;p=linux-2.6-omap-h63xx.git

[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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 982cf62ab66..9ab06e0dad4 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -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 */