Commit 7b666653 authored by Sergei Shtylylov's avatar Sergei Shtylylov Committed by Linus Torvalds
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[PATCH] Au1550 AC'97 OSS driver spinlock fixes 



We have found some issues with Au1550 AC'97 OSS driver in 2.6
(sound/oss/au1550_ac97.c), though it also should concern 2.4 driver
(drivers/sound/au1550_psc.c).

start_dac() grabs a spinlock already held by its caller, au1550_write().
This doesn't show up with the standard UP spinlock impelmentation but when
the different one (mutex based) is in use, a lockup happens.

And the interrupt handlers also didn't grab the spinlock -- that's OK in
the usual kernel but not when the IRQ handlers are threaded.  So, they're
grabbing the spinlock now (as every correct interrupt handler should do).

Signed-off-by: default avatarKonstantin Baidarov <kbaidarov@ru.mvista.com>
Signed-off-by: default avatarSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2f40fb72

sound/oss/au1550_ac97.c

+18 −11
Original line number Diff line number Diff line
@@ -578,17 +578,15 @@ set_recv_slots(int num_channels) 
	} while ((stat & PSC_AC97STAT_DR) == 0);

}



/* Hold spinlock for both start_dac() and start_adc() calls */

static void

start_dac(struct au1550_state *s)

{

	struct dmabuf  *db = &s->dma_dac;

	unsigned long   flags;



	if (!db->stopped)

		return;



	spin_lock_irqsave(&s->lock, flags);



	set_xmit_slots(db->num_channels);

	au_writel(PSC_AC97PCR_TC, PSC_AC97PCR);

	au_sync();
@@ -598,8 +596,6 @@ start_dac(struct au1550_state *s) 
	au1xxx_dbdma_start(db->dmanr);



	db->stopped = 0;



	spin_unlock_irqrestore(&s->lock, flags);

}



static void
@@ -718,7 +714,6 @@ prog_dmabuf_dac(struct au1550_state *s) 
}





/* hold spinlock for the following */

static void

dac_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs)

{
@@ -726,6 +721,8 @@ dac_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
	struct dmabuf  *db = &s->dma_dac;

	u32	ac97c_stat;



	spin_lock(&s->lock);



	ac97c_stat = au_readl(PSC_AC97STAT);

	if (ac97c_stat & (AC97C_XU | AC97C_XO | AC97C_TE))

		pr_debug("AC97C status = 0x%08x\n", ac97c_stat);
@@ -747,6 +744,8 @@ dac_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
	/* wake up anybody listening */

	if (waitqueue_active(&db->wait))

		wake_up(&db->wait);



	spin_unlock(&s->lock);

}
@@ -758,6 +757,8 @@ adc_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
	u32	obytes;

	char	*obuf;



	spin_lock(&s->lock);



	/* Pull the buffer from the dma queue.

	*/

	au1xxx_dbdma_get_dest(dp->dmanr, (void *)(&obuf), &obytes);
@@ -765,6 +766,7 @@ adc_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
	if ((dp->count + obytes) > dp->dmasize) {

		/* Overrun. Stop ADC and log the error

		*/

		spin_unlock(&s->lock);

		stop_adc(s);

		dp->error++;

		err("adc overrun");
@@ -787,6 +789,7 @@ adc_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs) 
	if (waitqueue_active(&dp->wait))

		wake_up(&dp->wait);



	spin_unlock(&s->lock);

}



static loff_t
@@ -1048,9 +1051,9 @@ au1550_read(struct file *file, char *buffer, size_t count, loff_t *ppos) 
		/* wait for samples in ADC dma buffer

		*/

		do {

			spin_lock_irqsave(&s->lock, flags);

			if (db->stopped)

				start_adc(s);

			spin_lock_irqsave(&s->lock, flags);

			avail = db->count;

			if (avail <= 0)

				__set_current_state(TASK_INTERRUPTIBLE);
@@ -1570,15 +1573,19 @@ au1550_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 
		if (get_user(val, (int *) arg))

			return -EFAULT;

		if (file->f_mode & FMODE_READ) {

			if (val & PCM_ENABLE_INPUT)

			if (val & PCM_ENABLE_INPUT) {

				spin_lock_irqsave(&s->lock, flags);

				start_adc(s);

			else

				spin_unlock_irqrestore(&s->lock, flags);

			} else

				stop_adc(s);

		}

		if (file->f_mode & FMODE_WRITE) {

			if (val & PCM_ENABLE_OUTPUT)

			if (val & PCM_ENABLE_OUTPUT) {

				spin_lock_irqsave(&s->lock, flags);

				start_dac(s);

			else

				spin_unlock_irqrestore(&s->lock, flags);

			} else

				stop_dac(s);

		}

		return 0;

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