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Commit 4b7afb0d authored by Stas Sergeev's avatar Stas Sergeev Committed by Takashi Iwai
Browse files

snd-pcsp: use HRTIMER_CB_SOFTIRQ 



Change HRTIMER_CB_IRQSAFE to HRTIMER_CB_SOFTIRQ,
as suggested by Thomas Gleixner.
That solves the lock dependancy reported in
Bug #10701.
That also allows to call hrtimer_start()
directly, tasklet "stupid hack" removed.

Signed-off-by: default avatarStas Sergeev <stsp@aknet.ru>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 8033c6e9

sound/drivers/pcsp/pcsp.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -96,7 +96,7 @@ static int __devinit snd_card_pcsp_probe(int devnum, struct device *dev) 
		return -EINVAL;

		return -EINVAL;





	hrtimer_init(&pcsp_chip.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

	hrtimer_init(&pcsp_chip.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

	pcsp_chip.timer.cb_mode = HRTIMER_CB_IRQSAFE;

	pcsp_chip.timer.cb_mode = HRTIMER_CB_SOFTIRQ;

	pcsp_chip.timer.function = pcsp_do_timer;

	pcsp_chip.timer.function = pcsp_do_timer;





	card = snd_card_new(index, id, THIS_MODULE, 0);

	card = snd_card_new(index, id, THIS_MODULE, 0);

sound/drivers/pcsp/pcsp_lib.c

+4 −33
Original line number Original line Diff line number Diff line
@@ -9,7 +9,6 @@ 
#include <linux/module.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/moduleparam.h>

#include <sound/pcm.h>

#include <sound/pcm.h>

#include <linux/interrupt.h>

#include <asm/io.h>

#include <asm/io.h>

#include "pcsp.h"

#include "pcsp.h"
@@ -20,34 +19,8 @@ MODULE_PARM_DESC(nforce_wa, "Apply NForce chipset workaround " 




#define DMIX_WANTS_S16	1

#define DMIX_WANTS_S16	1





static void pcsp_start_timer(unsigned long dummy)

{

	hrtimer_start(&pcsp_chip.timer, ktime_set(0, 0), HRTIMER_MODE_REL);

}



/*

 * We need the hrtimer_start as a tasklet to avoid

 * the nasty locking problem. :(

 * The problem:

 * - The timer handler is called with the cpu_base->lock

 *   already held by hrtimer code.

 * - snd_pcm_period_elapsed() takes the

 *   substream->self_group.lock.

 * So far so good.

 * But the snd_pcsp_trigger() is called with the

 * substream->self_group.lock held, and it calls

 * hrtimer_start(), which takes the cpu_base->lock.

 * You see the problem. We have the code pathes

 * which take two locks in a reverse order. This

 * can deadlock and the lock validator complains.

 * The only solution I could find was to move the

 * hrtimer_start() into a tasklet. -stsp

 */

static DECLARE_TASKLET(pcsp_start_timer_tasklet, pcsp_start_timer, 0);



enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle)

enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle)

{

{

	unsigned long flags;

	unsigned char timer_cnt, val;

	unsigned char timer_cnt, val;

	int fmt_size, periods_elapsed;

	int fmt_size, periods_elapsed;

	u64 ns;

	u64 ns;
@@ -66,9 +39,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) 
		return HRTIMER_RESTART;

		return HRTIMER_RESTART;

	}

	}





	/* hrtimer calls us from both hardirq and softirq contexts,

	spin_lock_irq(&chip->substream_lock);

	 * so irqsave :( */

	spin_lock_irqsave(&chip->substream_lock, flags);

	/* Takashi Iwai says regarding this extra lock:

	/* Takashi Iwai says regarding this extra lock:





	If the irq handler handles some data on the DMA buffer, it should

	If the irq handler handles some data on the DMA buffer, it should
@@ -139,7 +110,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) 
		chip->period_ptr %= buffer_bytes;

		chip->period_ptr %= buffer_bytes;

	}

	}





	spin_unlock_irqrestore(&chip->substream_lock, flags);

	spin_unlock_irq(&chip->substream_lock);





	if (!atomic_read(&chip->timer_active))

	if (!atomic_read(&chip->timer_active))

		return HRTIMER_NORESTART;

		return HRTIMER_NORESTART;
@@ -153,7 +124,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) 
exit_nr_unlock2:

exit_nr_unlock2:

	snd_pcm_stream_unlock(substream);

	snd_pcm_stream_unlock(substream);

exit_nr_unlock1:

exit_nr_unlock1:

	spin_unlock_irqrestore(&chip->substream_lock, flags);

	spin_unlock_irq(&chip->substream_lock);

	return HRTIMER_NORESTART;

	return HRTIMER_NORESTART;

}

}
@@ -174,7 +145,7 @@ static void pcsp_start_playing(struct snd_pcsp *chip) 
	atomic_set(&chip->timer_active, 1);

	atomic_set(&chip->timer_active, 1);

	chip->thalf = 0;

	chip->thalf = 0;





	tasklet_schedule(&pcsp_start_timer_tasklet);

	hrtimer_start(&pcsp_chip.timer, ktime_set(0, 0), HRTIMER_MODE_REL);

}

}





static void pcsp_stop_playing(struct snd_pcsp *chip)

static void pcsp_stop_playing(struct snd_pcsp *chip)