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Message-Id: <20121114053935.384898333@decadent.org.uk>
Date: Wed, 14 Nov 2012 05:39:44 +0000
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
Takashi Iwai <tiwai@...e.de>,
Matthieu CASTET <matthieu.castet@...rot.com>
Subject: [ 11/82] ALSA: Add a reference counter to card instance
3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Takashi Iwai <tiwai@...e.de>
commit a0830dbd4e42b38aefdf3fb61ba5019a1a99ea85 upstream.
For more strict protection for wild disconnections, a refcount is
introduced to the card instance, and let it up/down when an object is
referred via snd_lookup_*() in the open ops.
The free-after-last-close check is also changed to check this refcount
instead of the empty list, too.
Reported-by: Matthieu CASTET <matthieu.castet@...rot.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
include/sound/core.h | 3 +++
sound/core/control.c | 3 +++
sound/core/hwdep.c | 5 ++++-
sound/core/init.c | 50 +++++++++++++++++++++++++++-------------------
sound/core/oss/mixer_oss.c | 10 ++++++++--
sound/core/oss/pcm_oss.c | 2 ++
sound/core/pcm_native.c | 9 +++++++--
sound/core/rawmidi.c | 6 +++++-
sound/core/sound.c | 11 ++++++++--
sound/core/sound_oss.c | 10 ++++++++--
10 files changed, 79 insertions(+), 30 deletions(-)
diff --git a/include/sound/core.h b/include/sound/core.h
index 3be5ab7..222f11e 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -132,6 +132,7 @@ struct snd_card {
int shutdown; /* this card is going down */
int free_on_last_close; /* free in context of file_release */
wait_queue_head_t shutdown_sleep;
+ atomic_t refcount; /* refcount for disconnection */
struct device *dev; /* device assigned to this card */
struct device *card_dev; /* cardX object for sysfs */
@@ -189,6 +190,7 @@ struct snd_minor {
const struct file_operations *f_ops; /* file operations */
void *private_data; /* private data for f_ops->open */
struct device *dev; /* device for sysfs */
+ struct snd_card *card_ptr; /* assigned card instance */
};
/* return a device pointer linked to each sound device as a parent */
@@ -295,6 +297,7 @@ int snd_card_info_done(void);
int snd_component_add(struct snd_card *card, const char *component);
int snd_card_file_add(struct snd_card *card, struct file *file);
int snd_card_file_remove(struct snd_card *card, struct file *file);
+void snd_card_unref(struct snd_card *card);
#define snd_card_set_dev(card, devptr) ((card)->dev = (devptr))
diff --git a/sound/core/control.c b/sound/core/control.c
index 819a5c5..699ccf5 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -86,6 +86,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
write_lock_irqsave(&card->ctl_files_rwlock, flags);
list_add_tail(&ctl->list, &card->ctl_files);
write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
+ snd_card_unref(card);
return 0;
__error:
@@ -93,6 +94,8 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
__error2:
snd_card_file_remove(card, file);
__error1:
+ if (card)
+ snd_card_unref(card);
return err;
}
diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index 75ea16f..53a6ba5 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -100,8 +100,10 @@ static int snd_hwdep_open(struct inode *inode, struct file * file)
if (hw == NULL)
return -ENODEV;
- if (!try_module_get(hw->card->module))
+ if (!try_module_get(hw->card->module)) {
+ snd_card_unref(hw->card);
return -EFAULT;
+ }
init_waitqueue_entry(&wait, current);
add_wait_queue(&hw->open_wait, &wait);
@@ -148,6 +150,7 @@ static int snd_hwdep_open(struct inode *inode, struct file * file)
mutex_unlock(&hw->open_mutex);
if (err < 0)
module_put(hw->card->module);
+ snd_card_unref(hw->card);
return err;
}
diff --git a/sound/core/init.c b/sound/core/init.c
index 3ac49b1..fa0f35b 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -212,6 +212,7 @@ int snd_card_create(int idx, const char *xid,
spin_lock_init(&card->files_lock);
INIT_LIST_HEAD(&card->files_list);
init_waitqueue_head(&card->shutdown_sleep);
+ atomic_set(&card->refcount, 0);
#ifdef CONFIG_PM
mutex_init(&card->power_lock);
init_waitqueue_head(&card->power_sleep);
@@ -445,21 +446,36 @@ static int snd_card_do_free(struct snd_card *card)
return 0;
}
+/**
+ * snd_card_unref - release the reference counter
+ * @card: the card instance
+ *
+ * Decrements the reference counter. When it reaches to zero, wake up
+ * the sleeper and call the destructor if needed.
+ */
+void snd_card_unref(struct snd_card *card)
+{
+ if (atomic_dec_and_test(&card->refcount)) {
+ wake_up(&card->shutdown_sleep);
+ if (card->free_on_last_close)
+ snd_card_do_free(card);
+ }
+}
+EXPORT_SYMBOL(snd_card_unref);
+
int snd_card_free_when_closed(struct snd_card *card)
{
- int free_now = 0;
- int ret = snd_card_disconnect(card);
- if (ret)
- return ret;
+ int ret;
- spin_lock(&card->files_lock);
- if (list_empty(&card->files_list))
- free_now = 1;
- else
- card->free_on_last_close = 1;
- spin_unlock(&card->files_lock);
+ atomic_inc(&card->refcount);
+ ret = snd_card_disconnect(card);
+ if (ret) {
+ atomic_dec(&card->refcount);
+ return ret;
+ }
- if (free_now)
+ card->free_on_last_close = 1;
+ if (atomic_dec_and_test(&card->refcount))
snd_card_do_free(card);
return 0;
}
@@ -473,7 +489,7 @@ int snd_card_free(struct snd_card *card)
return ret;
/* wait, until all devices are ready for the free operation */
- wait_event(card->shutdown_sleep, list_empty(&card->files_list));
+ wait_event(card->shutdown_sleep, !atomic_read(&card->refcount));
snd_card_do_free(card);
return 0;
}
@@ -854,6 +870,7 @@ int snd_card_file_add(struct snd_card *card, struct file *file)
return -ENODEV;
}
list_add(&mfile->list, &card->files_list);
+ atomic_inc(&card->refcount);
spin_unlock(&card->files_lock);
return 0;
}
@@ -876,7 +893,6 @@ EXPORT_SYMBOL(snd_card_file_add);
int snd_card_file_remove(struct snd_card *card, struct file *file)
{
struct snd_monitor_file *mfile, *found = NULL;
- int last_close = 0;
spin_lock(&card->files_lock);
list_for_each_entry(mfile, &card->files_list, list) {
@@ -891,19 +907,13 @@ int snd_card_file_remove(struct snd_card *card, struct file *file)
break;
}
}
- if (list_empty(&card->files_list))
- last_close = 1;
spin_unlock(&card->files_lock);
- if (last_close) {
- wake_up(&card->shutdown_sleep);
- if (card->free_on_last_close)
- snd_card_do_free(card);
- }
if (!found) {
snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
return -ENOENT;
}
kfree(found);
+ snd_card_unref(card);
return 0;
}
diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index 18297f7..05395aa 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -52,14 +52,19 @@ static int snd_mixer_oss_open(struct inode *inode, struct file *file)
SNDRV_OSS_DEVICE_TYPE_MIXER);
if (card == NULL)
return -ENODEV;
- if (card->mixer_oss == NULL)
+ if (card->mixer_oss == NULL) {
+ snd_card_unref(card);
return -ENODEV;
+ }
err = snd_card_file_add(card, file);
- if (err < 0)
+ if (err < 0) {
+ snd_card_unref(card);
return err;
+ }
fmixer = kzalloc(sizeof(*fmixer), GFP_KERNEL);
if (fmixer == NULL) {
snd_card_file_remove(card, file);
+ snd_card_unref(card);
return -ENOMEM;
}
fmixer->card = card;
@@ -68,6 +73,7 @@ static int snd_mixer_oss_open(struct inode *inode, struct file *file)
if (!try_module_get(card->module)) {
kfree(fmixer);
snd_card_file_remove(card, file);
+ snd_card_unref(card);
return -EFAULT;
}
return 0;
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 3cc4b86..f3cf781 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2457,6 +2457,8 @@ static int snd_pcm_oss_open(struct inode *inode, struct file *file)
__error2:
snd_card_file_remove(pcm->card, file);
__error1:
+ if (pcm)
+ snd_card_unref(pcm->card);
return err;
}
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index e62da93..c67994d 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1628,6 +1628,7 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
_end:
write_unlock_irq(&snd_pcm_link_rwlock);
up_write(&snd_pcm_link_rwsem);
+ snd_card_unref(substream1->pcm->card);
fput(file);
return res;
}
@@ -2100,7 +2101,9 @@ static int snd_pcm_playback_open(struct inode *inode, struct file *file)
return err;
pcm = snd_lookup_minor_data(iminor(inode),
SNDRV_DEVICE_TYPE_PCM_PLAYBACK);
- return snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_PLAYBACK);
+ err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_PLAYBACK);
+ snd_card_unref(pcm->card);
+ return err;
}
static int snd_pcm_capture_open(struct inode *inode, struct file *file)
@@ -2111,7 +2114,9 @@ static int snd_pcm_capture_open(struct inode *inode, struct file *file)
return err;
pcm = snd_lookup_minor_data(iminor(inode),
SNDRV_DEVICE_TYPE_PCM_CAPTURE);
- return snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_CAPTURE);
+ err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_CAPTURE);
+ snd_card_unref(pcm->card);
+ return err;
}
static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ebf6e49..7d4f62a 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -379,8 +379,10 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
if (rmidi == NULL)
return -ENODEV;
- if (!try_module_get(rmidi->card->module))
+ if (!try_module_get(rmidi->card->module)) {
+ snd_card_unref(rmidi->card);
return -ENXIO;
+ }
mutex_lock(&rmidi->open_mutex);
card = rmidi->card;
@@ -440,6 +442,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
#endif
file->private_data = rawmidi_file;
mutex_unlock(&rmidi->open_mutex);
+ snd_card_unref(rmidi->card);
return 0;
__error:
@@ -447,6 +450,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
__error_card:
mutex_unlock(&rmidi->open_mutex);
module_put(rmidi->card->module);
+ snd_card_unref(rmidi->card);
return err;
}
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 828af35..f188976 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -99,6 +99,10 @@ static void snd_request_other(int minor)
*
* Checks that a minor device with the specified type is registered, and returns
* its user data pointer.
+ *
+ * This function increments the reference counter of the card instance
+ * if an associated instance with the given minor number and type is found.
+ * The caller must call snd_card_unref() appropriately later.
*/
void *snd_lookup_minor_data(unsigned int minor, int type)
{
@@ -109,9 +113,11 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
return NULL;
mutex_lock(&sound_mutex);
mreg = snd_minors[minor];
- if (mreg && mreg->type == type)
+ if (mreg && mreg->type == type) {
private_data = mreg->private_data;
- else
+ if (mreg->card_ptr)
+ atomic_inc(&mreg->card_ptr->refcount);
+ } else
private_data = NULL;
mutex_unlock(&sound_mutex);
return private_data;
@@ -275,6 +281,7 @@ int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
preg->device = dev;
preg->f_ops = f_ops;
preg->private_data = private_data;
+ preg->card_ptr = card;
mutex_lock(&sound_mutex);
#ifdef CONFIG_SND_DYNAMIC_MINORS
minor = snd_find_free_minor(type);
diff --git a/sound/core/sound_oss.c b/sound/core/sound_oss.c
index c700920..7442c7a 100644
--- a/sound/core/sound_oss.c
+++ b/sound/core/sound_oss.c
@@ -40,6 +40,9 @@
static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS];
static DEFINE_MUTEX(sound_oss_mutex);
+/* NOTE: This function increments the refcount of the associated card like
+ * snd_lookup_minor_data(); the caller must call snd_card_unref() appropriately
+ */
void *snd_lookup_oss_minor_data(unsigned int minor, int type)
{
struct snd_minor *mreg;
@@ -49,9 +52,11 @@ void *snd_lookup_oss_minor_data(unsigned int minor, int type)
return NULL;
mutex_lock(&sound_oss_mutex);
mreg = snd_oss_minors[minor];
- if (mreg && mreg->type == type)
+ if (mreg && mreg->type == type) {
private_data = mreg->private_data;
- else
+ if (mreg->card_ptr)
+ atomic_inc(&mreg->card_ptr->refcount);
+ } else
private_data = NULL;
mutex_unlock(&sound_oss_mutex);
return private_data;
@@ -123,6 +128,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
preg->device = dev;
preg->f_ops = f_ops;
preg->private_data = private_data;
+ preg->card_ptr = card;
mutex_lock(&sound_oss_mutex);
snd_oss_minors[minor] = preg;
minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);
--
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