BKL removal from ALSA core

BKL removal from ALSA core

[Takashi Iwai]

Hi,
I recently cleaned up ALSA core code a bit.  The first attemp is the
removal of BKL, at least, in ALSA side.  There are still in sound_core.c
and OSS drivers, but who cares ;)

The patches below are in sound git tree topic/bkl branch.

 [PATCH 1/3] ALSA: pcm - Remove BKL from async callback
 [PATCH 2/3] ALSA: info - Remove BKL
 [PATCH 3/3] ALSA: Remove BKL from open multiplexer


Takashi

[PATCH 1/3] ALSA: pcm - Remove BKL from async callback

[Takashi Iwai]

It's simply calling fasync_helper().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm_native.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 8728876..cadba30 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3303,18 +3303,13 @@ static int snd_pcm_fasync(int fd, struct file * file, int on)
 	struct snd_pcm_file * pcm_file;
 	struct snd_pcm_substream *substream;
 	struct snd_pcm_runtime *runtime;
-	int err = -ENXIO;
 
-	lock_kernel();
 	pcm_file = file->private_data;
 	substream = pcm_file->substream;
 	if (PCM_RUNTIME_CHECK(substream))
-		goto out;
+		return -ENXIO;
 	runtime = substream->runtime;
-	err = fasync_helper(fd, file, on, &runtime->fasync);
-out:
-	unlock_kernel();
-	return err;
+	return fasync_helper(fd, file, on, &runtime->fasync);
 }
 
 /*
-- 
1.7.0.4

[PATCH 2/3] ALSA: info - Remove BKL

[Takashi Iwai]

Use the fine-grained mutex for the assigned info object, instead.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/info.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/core/info.c b/sound/core/info.c
index d749a0d..fe83661 100644
--- a/sound/core/info.c
+++ b/sound/core/info.c
@@ -167,7 +167,7 @@ static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
 
 	data = file->private_data;
 	entry = data->entry;
-	lock_kernel();
+	mutex_lock(&entry->access);
 	switch (entry->content) {
 	case SNDRV_INFO_CONTENT_TEXT:
 		switch (orig) {
@@ -196,7 +196,7 @@ static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
 	}
 	ret = -ENXIO;
 out:
-	unlock_kernel();
+	mutex_unlock(&entry->access);
 	return ret;
 }
 
-- 
1.7.0.4

[PATCH 3/3] ALSA: Remove BKL from open multiplexer

[Takashi Iwai]

Use a local mutex instead of BKL.  This should suffice since each device
type has also its open_mutex.
Also, a bit of clean-up of the legacy device auto-loading code.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/sound.c |   73 +++++++++++++++++++++++++++-------------------------
 1 files changed, 38 insertions(+), 35 deletions(-)

diff --git a/sound/core/sound.c b/sound/core/sound.c
index 563d196..ac42af4 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -120,7 +120,29 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
 
 EXPORT_SYMBOL(snd_lookup_minor_data);
 
-static int __snd_open(struct inode *inode, struct file *file)
+#ifdef CONFIG_MODULES
+static struct snd_minor *autoload_device(unsigned int minor)
+{
+	int dev;
+	mutex_unlock(&sound_mutex); /* release lock temporarily */
+	dev = SNDRV_MINOR_DEVICE(minor);
+	if (dev == SNDRV_MINOR_CONTROL) {
+		/* /dev/aloadC? */
+		int card = SNDRV_MINOR_CARD(minor);
+		if (snd_cards[card] == NULL)
+			snd_request_card(card);
+	} else if (dev == SNDRV_MINOR_GLOBAL) {
+		/* /dev/aloadSEQ */
+		snd_request_other(minor);
+	}
+	mutex_lock(&sound_mutex); /* reacuire lock */
+	return snd_minors[minor];
+}
+#else /* !CONFIG_MODULES */
+#define autoload_device(minor)	NULL
+#endif /* CONFIG_MODULES */
+
+static int snd_open(struct inode *inode, struct file *file)
 {
 	unsigned int minor = iminor(inode);
 	struct snd_minor *mptr = NULL;
@@ -129,55 +151,36 @@ static int __snd_open(struct inode *inode, struct file *file)
 
 	if (minor >= ARRAY_SIZE(snd_minors))
 		return -ENODEV;
+	mutex_lock(&sound_mutex);
 	mptr = snd_minors[minor];
 	if (mptr == NULL) {
-#ifdef CONFIG_MODULES
-		int dev = SNDRV_MINOR_DEVICE(minor);
-		if (dev == SNDRV_MINOR_CONTROL) {
-			/* /dev/aloadC? */
-			int card = SNDRV_MINOR_CARD(minor);
-			if (snd_cards[card] == NULL)
-				snd_request_card(card);
-		} else if (dev == SNDRV_MINOR_GLOBAL) {
-			/* /dev/aloadSEQ */
-			snd_request_other(minor);
-		}
-#ifndef CONFIG_SND_DYNAMIC_MINORS
-		/* /dev/snd/{controlC?,seq} */
-		mptr = snd_minors[minor];
-		if (mptr == NULL)
-#endif
-#endif
+		mptr = autoload_device(minor);
+		if (!mptr) {
+			mutex_unlock(&sound_mutex);
 			return -ENODEV;
+		}
 	}
 	old_fops = file->f_op;
 	file->f_op = fops_get(mptr->f_ops);
 	if (file->f_op == NULL) {
 		file->f_op = old_fops;
-		return -ENODEV;
+		err = -ENODEV;
 	}
-	if (file->f_op->open)
+	mutex_unlock(&sound_mutex);
+	if (err < 0)
+		return err;
+
+	if (file->f_op->open) {
 		err = file->f_op->open(inode, file);
-	if (err) {
-		fops_put(file->f_op);
-		file->f_op = fops_get(old_fops);
+		if (err) {
+			fops_put(file->f_op);
+			file->f_op = fops_get(old_fops);
+		}
 	}
 	fops_put(old_fops);
 	return err;
 }
 
-
-/* BKL pushdown: nasty #ifdef avoidance wrapper */
-static int snd_open(struct inode *inode, struct file *file)
-{
-	int ret;
-
-	lock_kernel();
-	ret = __snd_open(inode, file);
-	unlock_kernel();
-	return ret;
-}
-
 static const struct file_operations snd_fops =
 {
 	.owner =	THIS_MODULE,
-- 
1.7.0.4