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Subject[PATCH] ALSA: pcm: Hide local_irq_disable/enable() and local_irqsave/restore()
Date
From: Anna-Maria Gleixner <anna-maria@linutronix.de>

The snd_pcm_stream_lock_irq*() functions decouple disabling interrupts
from the actual locking process. This does not work as expected if the
locking primitives are replaced like on preempt-rt.

Provide one function for locking which uses correct locking primitives.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
sound/core/pcm_native.c | 85 +++++++++++++++++++++++++++--------------
1 file changed, 57 insertions(+), 28 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index d18b3982548b..92c10fc838e9 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -99,6 +99,57 @@ static inline void down_write_nonblock(struct rw_semaphore *lock)
cond_resched();
}

+#define PCM_LOCK_DEFAULT 0
+#define PCM_LOCK_IRQ 1
+#define PCM_LOCK_IRQSAVE 2
+
+static unsigned long __snd_pcm_stream_lock_mode(struct snd_pcm_substream *substream,
+ unsigned int mode)
+{
+ unsigned long flags = 0;
+ if (substream->pcm->nonatomic) {
+ down_read_nested(&snd_pcm_link_rwsem, SINGLE_DEPTH_NESTING);
+ mutex_lock(&substream->self_group.mutex);
+ } else {
+ switch (mode) {
+ case PCM_LOCK_DEFAULT:
+ read_lock(&snd_pcm_link_rwlock);
+ break;
+ case PCM_LOCK_IRQ:
+ read_lock_irq(&snd_pcm_link_rwlock);
+ break;
+ case PCM_LOCK_IRQSAVE:
+ read_lock_irqsave(&snd_pcm_link_rwlock, flags);
+ break;
+ }
+ spin_lock(&substream->self_group.lock);
+ }
+ return flags;
+}
+
+static void __snd_pcm_stream_unlock_mode(struct snd_pcm_substream *substream,
+ unsigned int mode, unsigned long flags)
+{
+ if (substream->pcm->nonatomic) {
+ mutex_unlock(&substream->self_group.mutex);
+ up_read(&snd_pcm_link_rwsem);
+ } else {
+ spin_unlock(&substream->self_group.lock);
+
+ switch (mode) {
+ case PCM_LOCK_DEFAULT:
+ read_unlock(&snd_pcm_link_rwlock);
+ break;
+ case PCM_LOCK_IRQ:
+ read_unlock_irq(&snd_pcm_link_rwlock);
+ break;
+ case PCM_LOCK_IRQSAVE:
+ read_unlock_irqrestore(&snd_pcm_link_rwlock, flags);
+ break;
+ }
+ }
+}
+
/**
* snd_pcm_stream_lock - Lock the PCM stream
* @substream: PCM substream
@@ -109,13 +160,7 @@ static inline void down_write_nonblock(struct rw_semaphore *lock)
*/
void snd_pcm_stream_lock(struct snd_pcm_substream *substream)
{
- if (substream->pcm->nonatomic) {
- down_read_nested(&snd_pcm_link_rwsem, SINGLE_DEPTH_NESTING);
- mutex_lock(&substream->self_group.mutex);
- } else {
- read_lock(&snd_pcm_link_rwlock);
- spin_lock(&substream->self_group.lock);
- }
+ __snd_pcm_stream_lock_mode(substream, PCM_LOCK_DEFAULT);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);

@@ -127,13 +172,7 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);
*/
void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)
{
- if (substream->pcm->nonatomic) {
- mutex_unlock(&substream->self_group.mutex);
- up_read(&snd_pcm_link_rwsem);
- } else {
- spin_unlock(&substream->self_group.lock);
- read_unlock(&snd_pcm_link_rwlock);
- }
+ __snd_pcm_stream_unlock_mode(substream, PCM_LOCK_DEFAULT, 0);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);

@@ -147,9 +186,7 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);
*/
void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
{
- if (!substream->pcm->nonatomic)
- local_irq_disable();
- snd_pcm_stream_lock(substream);
+ __snd_pcm_stream_lock_mode(substream, PCM_LOCK_IRQ);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);

@@ -161,19 +198,13 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);
*/
void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream)
{
- snd_pcm_stream_unlock(substream);
- if (!substream->pcm->nonatomic)
- local_irq_enable();
+ __snd_pcm_stream_unlock_mode(substream, PCM_LOCK_IRQ, 0);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irq);

unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream)
{
- unsigned long flags = 0;
- if (!substream->pcm->nonatomic)
- local_irq_save(flags);
- snd_pcm_stream_lock(substream);
- return flags;
+ return __snd_pcm_stream_lock_mode(substream, PCM_LOCK_IRQSAVE);
}
EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);

@@ -187,9 +218,7 @@ EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);
void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
unsigned long flags)
{
- snd_pcm_stream_unlock(substream);
- if (!substream->pcm->nonatomic)
- local_irq_restore(flags);
+ __snd_pcm_stream_unlock_mode(substream, PCM_LOCK_IRQSAVE, flags);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irqrestore);

--
2.17.0
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