On 08/24/12 13:03, Sean Young wrote:
> On Wed, Aug 22, 2012 at 10:50:35PM +0300, Timo Kokkonen wrote:
>> The lirc-dev expects the ir-code to be transmitted when the write call
>> returns back to the user space. We should not leave TX ongoing no
>> matter what is the reason we return to the user space. Easiest
>> solution for that is to simply remove interruptible sleeps.
>>
>> The first wait_event_interruptible is thus replaced with return -EBUSY
>> in case there is still ongoing transfer. This should suffice as the
>> concept of sending multiple codes in parallel does not make sense.
>>
>> The second wait_event_interruptible call is replaced with
>> wait_even_timeout with a fixed and safe timeout that should prevent
>> the process from getting stuck in kernel for too long.
>>
>> Also, from now on we will force the TX to stop before we return from
>> write call. If the TX happened to time out for some reason, we should
>> not leave the HW transmitting anything.
>>
>> Signed-off-by: Timo Kokkonen <timo.t.kokko...@iki.fi>
>> ---
>> drivers/media/rc/ir-rx51.c | 39 ++++++++++++++++++++++++++++-----------
>> 1 file changed, 28 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/media/rc/ir-rx51.c b/drivers/media/rc/ir-rx51.c
>> index 9487dd3..a7b787a 100644
>> --- a/drivers/media/rc/ir-rx51.c
>> +++ b/drivers/media/rc/ir-rx51.c
>> @@ -74,6 +74,19 @@ static void lirc_rx51_off(struct lirc_rx51 *lirc_rx51)
>> OMAP_TIMER_TRIGGER_NONE);
>> }
>>
>> +static void lirc_rx51_stop_tx(struct lirc_rx51 *lirc_rx51)
>> +{
>> + if (lirc_rx51->wbuf_index < 0)
>> + return;
>> +
>> + lirc_rx51_off(lirc_rx51);
>> + lirc_rx51->wbuf_index = -1;
>> + omap_dm_timer_stop(lirc_rx51->pwm_timer);
>> + omap_dm_timer_stop(lirc_rx51->pulse_timer);
>> + omap_dm_timer_set_int_enable(lirc_rx51->pulse_timer, 0);
>> + wake_up_interruptible(&lirc_rx51->wqueue);
>
> Unless I'm mistaken, wait_up_interruptable() won't wake up any
> non-interruptable sleepers. Should this not be wake_up()?
>
Thanks for pointing out that. I guess I never noticed that because I'm
using a timeout with the wait, so it will wake up anyway. I'll fix it.
-Timo
>> +}
>> +
>> static int init_timing_params(struct lirc_rx51 *lirc_rx51)
>> {
>> u32 load, match;
>> @@ -160,13 +173,7 @@ static irqreturn_t lirc_rx51_interrupt_handler(int irq,
>> void *ptr)
>>
>> return IRQ_HANDLED;
>> end:
>> - /* Stop TX here */
>> - lirc_rx51_off(lirc_rx51);
>> - lirc_rx51->wbuf_index = -1;
>> - omap_dm_timer_stop(lirc_rx51->pwm_timer);
>> - omap_dm_timer_stop(lirc_rx51->pulse_timer);
>> - omap_dm_timer_set_int_enable(lirc_rx51->pulse_timer, 0);
>> - wake_up_interruptible(&lirc_rx51->wqueue);
>> + lirc_rx51_stop_tx(lirc_rx51);
>>
>> return IRQ_HANDLED;
>> }
>> @@ -246,8 +253,9 @@ static ssize_t lirc_rx51_write(struct file *file, const
>> char *buf,
>> if ((count > WBUF_LEN) || (count % 2 == 0))
>> return -EINVAL;
>>
>> - /* Wait any pending transfers to finish */
>> - wait_event_interruptible(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0);
>> + /* We can have only one transmit at a time */
>> + if (lirc_rx51->wbuf_index >= 0)
>> + return -EBUSY;
>>
>> if (copy_from_user(lirc_rx51->wbuf, buf, n))
>> return -EFAULT;
>> @@ -273,9 +281,18 @@ static ssize_t lirc_rx51_write(struct file *file, const
>> char *buf,
>>
>> /*
>> * Don't return back to the userspace until the transfer has
>> - * finished
>> + * finished. However, we wish to not spend any more than 500ms
>> + * in kernel. No IR code TX should ever take that long.
>> + */
>> + i = wait_event_timeout(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0,
>
> Note non-interruptable sleeper.
>
>> + HZ / 2);
>> +
>> + /*
>> + * Ensure transmitting has really stopped, even if the timers
>> + * went mad or something else happened that caused it still
>> + * sending out something.
>> */
>> - wait_event_interruptible(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0);
>> + lirc_rx51_stop_tx(lirc_rx51);
>>
>> /* We can sleep again */
>> lirc_rx51->pdata->set_max_mpu_wakeup_lat(lirc_rx51->dev, -1);
>> --
>> 1.7.12
>>
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