[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: Konstantin Baidarov <kbaidarov@ru.mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/sound/oss/au1550_ac97.c b/sound/oss/au1550_ac97.c
index 6b46a8a..b963c55 100644
--- a/sound/oss/au1550_ac97.c
+++ b/sound/oss/au1550_ac97.c
@@ -578,17 +578,15 @@
} 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 @@
au1xxx_dbdma_start(db->dmanr);
db->stopped = 0;
-
- spin_unlock_irqrestore(&s->lock, flags);
}
static void
@@ -718,7 +714,6 @@
}
-/* hold spinlock for the following */
static void
dac_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
@@ -726,6 +721,8 @@
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 @@
/* wake up anybody listening */
if (waitqueue_active(&db->wait))
wake_up(&db->wait);
+
+ spin_unlock(&s->lock);
}
@@ -758,6 +757,8 @@
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 @@
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 @@
if (waitqueue_active(&dp->wait))
wake_up(&dp->wait);
+ spin_unlock(&s->lock);
}
static loff_t
@@ -1048,9 +1051,9 @@
/* 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 @@
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;