From: Anna-Maria Gleixner <anna-maria@linutronix.de>
Date: Thu, 29 Mar 2018 17:09:27 +0200
Subject: [PATCH] ALSA: pcm: Hide local_irq_disable/enable() and
 local_irqsave/restore()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.16/older/patches-4.16.7-rt1.tar.xz

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(-)

--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -99,6 +99,57 @@ static inline void down_write_nonblock(s
 		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(s
  */
 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_ir
  */
 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_i
 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);