[ALSA] timers: add module refcounting for global timers

Modules: RTC timer driver,Timer Midlevel

Add a module pointer to the timer structure and use it for refcounting
instead of the card's module pointer to prevent the global timer
modules (rtctimer and hpetimer) from being removed while in use.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

include/sound/timer.h

@@ -88,6 +88,7 @@ struct _snd_timer_hardware {
 struct _snd_timer {
 	snd_timer_class_t tmr_class;
 	snd_card_t *card;
+	struct module *module;
 	int tmr_device;
 	int tmr_subdevice;
 	char id[64];

sound/core/rtctimer.c

@@ -124,7 +124,8 @@ static int __init rtctimer_init(void)
 
 	if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
 	    (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
-		snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
+		snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
+			   rtctimer_freq);
 		return -EINVAL;
 	}
 
@@ -133,6 +134,7 @@ static int __init rtctimer_init(void)
 	if (err < 0)
 		return err;
 
+	timer->module = THIS_MODULE;
 	strcpy(timer->name, "RTC timer");
 	timer->hw = rtc_hw;
 	timer->hw.resolution = NANO_SEC / rtctimer_freq;

sound/core/timer.c

@@ -113,7 +113,7 @@ static snd_timer_instance_t *snd_timer_instance_new(char *owner, snd_timer_t *ti
 	INIT_LIST_HEAD(&timeri->slave_active_head);
 
 	timeri->timer = timer;
-	if (timer && timer->card && !try_module_get(timer->card->module)) {
+	if (timer && !try_module_get(timer->module)) {
 		kfree(timeri->owner);
 		kfree(timeri);
 		return NULL;
@@ -363,8 +363,8 @@ int snd_timer_close(snd_timer_instance_t * timeri)
 		timeri->private_free(timeri);
 	kfree(timeri->owner);
 	kfree(timeri);
-	if (timer && timer->card)
-		module_put(timer->card->module);
+	if (timer)
+		module_put(timer->module);
 	return 0;
 }
 
@@ -787,6 +787,7 @@ int snd_timer_new(snd_card_t *card, char *id, snd_timer_id_t *tid, snd_timer_t *
 	spin_lock_init(&timer->lock);
 	tasklet_init(&timer->task_queue, snd_timer_tasklet, (unsigned long)timer);
 	if (card != NULL) {
+		timer->module = card->module;
 		if ((err = snd_device_new(card, SNDRV_DEV_TIMER, timer, &ops)) < 0) {
 			snd_timer_free(timer);
 			return err;