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Subject[PATCH 44/61] ALSA: snd_rtctimer: handle RTC interrupts with a tasklet
-stable review patch.  If anyone has any objections, please let us know.
------------------
From: <clemens@ladisch.de>

The calls to rtc_control() from inside the interrupt handler can
deadlock the RTC code, so move our interrupt handling code to a tasklet.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

---
sound/core/rtctimer.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
--- linux-2.6.18.1.orig/sound/core/rtctimer.c
+++ linux-2.6.18.1/sound/core/rtctimer.c
@@ -50,7 +50,9 @@ static int rtctimer_stop(struct snd_time
* The hardware dependent description for this timer.
*/
static struct snd_timer_hardware rtc_hw = {
- .flags = SNDRV_TIMER_HW_FIRST|SNDRV_TIMER_HW_AUTO,
+ .flags = SNDRV_TIMER_HW_AUTO |
+ SNDRV_TIMER_HW_FIRST |
+ SNDRV_TIMER_HW_TASKLET,
.ticks = 100000000L, /* FIXME: XXX */
.open = rtctimer_open,
.close = rtctimer_close,
@@ -60,6 +62,7 @@ static struct snd_timer_hardware rtc_hw

static int rtctimer_freq = RTC_FREQ; /* frequency */
static struct snd_timer *rtctimer;
+static struct tasklet_struct rtc_tasklet;
static rtc_task_t rtc_task;


@@ -81,6 +84,7 @@ rtctimer_close(struct snd_timer *t)
rtc_task_t *rtc = t->private_data;
if (rtc) {
rtc_unregister(rtc);
+ tasklet_kill(&rtc_tasklet);
t->private_data = NULL;
}
return 0;
@@ -105,12 +109,17 @@ rtctimer_stop(struct snd_timer *timer)
return 0;
}

+static void rtctimer_tasklet(unsigned long data)
+{
+ snd_timer_interrupt((struct snd_timer *)data, 1);
+}
+
/*
* interrupt
*/
static void rtctimer_interrupt(void *private_data)
{
- snd_timer_interrupt(private_data, 1);
+ tasklet_hi_schedule(private_data);
}


@@ -139,9 +148,11 @@ static int __init rtctimer_init(void)
timer->hw = rtc_hw;
timer->hw.resolution = NANO_SEC / rtctimer_freq;

+ tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
+
/* set up RTC callback */
rtc_task.func = rtctimer_interrupt;
- rtc_task.private_data = timer;
+ rtc_task.private_data = &rtc_tasklet;

err = snd_timer_global_register(timer);
if (err < 0) {
--
-
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