redonkable/remarkable-linux
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[S390] 3215: Remove tasklet.

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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>
This commit is contained in:
Heiko Carstens 2008-10-10 21:33:28 +02:00 committed by Martin Schwidefsky
parent 2332ce1a97
commit 408aec3c6c
1 changed files with 6 additions and 20 deletions
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26
drivers/s390/char/con3215.c
View file

@ -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 */