Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: schedule_timeout() semantics/usage? | From | Dag Brattli <> | Date | 21 Oct 1999 07:28:24 +0200 |
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Andrea Arcangeli <andrea@suse.de> writes:
> On Wed, 20 Oct 1999, David Hinds wrote: > > >Look at net/irda/*.c [..] > > /* Make sure nobody tries to transmit during the speed change */ > while (irda_lock((void *) &self->netdev.tbusy) == FALSE) { > WARNING(__FUNCTION__ "(), device locked!\n"); > current->state = TASK_INTERRUPTIBLE; > schedule_timeout(MSECS_TO_JIFFIES(10)); > > if (n++ > 10) { > WARNING(__FUNCTION__ "(), breaking loop!\n"); > break; > } > }
I've already sent a very large patch to Alan a couple of days ago, which removes all the schedule_timeout's from the lower parts of the IrDA stack. Instead I'm impl. things as state machines and do the timeouts using timers. Some code can look a bit hairy because of this, but it's working quite well.
struct irda_task; typedef int (*TASK_CALLBACK) (struct irda_task *task);
struct irda_task { queue_t q; magic_t magic;
TASK_STATE state; TASK_CALLBACK function; TASK_CALLBACK finished;
struct irda_task *parent; struct timer_list timer;
void *instance; /* Instance being called */ void *param; /* Parameter to be used by instance */ };
... then I can do things like this to make timeouts:
int tekram_reset(struct irda_task *task) { dongle_t *self = (dongle_t *) task->instance; int ret = 0;
DEBUG(2, __FUNCTION__ "()\n");
ASSERT(task != NULL, return -1;); /* Power off dongle */ self->set_dtr_rts(self->dev, FALSE, FALSE);
switch (task->state) { case IRDA_TASK_INIT: irda_task_next_state(task, IRDA_TASK_WAIT1);
/* Sleep 50 ms */ ret = MSECS_TO_JIFFIES(50); break; case IRDA_TASK_WAIT1: /* Clear DTR, Set RTS */ self->set_dtr_rts(self->dev, FALSE, TRUE);
irda_task_next_state(task, IRDA_TASK_WAIT2); /* Should sleep 1 ms, but 10 should not do any harm */ ret = MSECS_TO_JIFFIES(10); break;
There are a couple of helping functions as well, but I guess you get my point.
The reason is that the lower part is interrupt driven, and I previously had to use a user-space daemon to help me get the process context for doing schedule_timeout. Now there is no need for such a deamon anymore (at least if my patch goes in, and when I have done a few more patches to IrLAN ;-) Anyway, thanks for the info.
-- Dag
-- / Dag Brattli | The Linux-IrDA Project / // University of Tromsoe, Norway | Infrared communication for Linux // /// http://www.cs.uit.no/~dagb | http://www.cs.uit.no/linux-irda/ ///
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