ALSA: firewire: use managed-resource of fw unit device for private data

At present, private data of each driver in ALSA firewire stack is
allocated/freed by kernel slab allocator for corresponding unit on
IEEE 1394 bus. In this case, resource-managed slab allocator is
available to release memory object automatically just before releasing
device structure for the unit. This idea can prevent runtime from
memory leak due to programming mistakes.

This commit uses the allocator for the private data. These drivers
already use reference counter to maintain lifetime of device structure
for the unit by a pair of fw_unit_get()/fw_unit_put(). The private data
is safely released in a callback of 'struct snd_card.private_free().

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 4 insertions, 6 deletions

diff --git a/sound/firewire/motu/motu.c b/sound/firewire/motu/motu.c
index 300d31b6f191..fd5726424c7a 100644
--- a/sound/firewire/motu/motu.c
+++ b/sound/firewire/motu/motu.c
@@ -57,10 +57,9 @@ static void motu_free(struct snd_motu *motu)
         snd_motu_transaction_unregister(motu);
 
         snd_motu_stream_destroy_duplex(motu);
-        fw_unit_put(motu->unit);
 
         mutex_destroy(&motu->mutex);
-        kfree(motu);
+        fw_unit_put(motu->unit);
 }
 
 /*
@@ -143,14 +142,13 @@ static int motu_probe(struct fw_unit *unit,
         struct snd_motu *motu;
 
         /* Allocate this independently of sound card instance. */
-        motu = kzalloc(sizeof(struct snd_motu), GFP_KERNEL);
-        if (motu == NULL)
+        motu = devm_kzalloc(&unit->device, sizeof(struct snd_motu), GFP_KERNEL);
+        if (!motu)
                 return -ENOMEM;
-
-        motu->spec = (const struct snd_motu_spec *)entry->driver_data;
         motu->unit = fw_unit_get(unit);
         dev_set_drvdata(&unit->device, motu);
 
+        motu->spec = (const struct snd_motu_spec *)entry->driver_data;
         mutex_init(&motu->mutex);
         spin_lock_init(&motu->lock);
         init_waitqueue_head(&motu->hwdep_wait);