ALSA: hda - Add pseudo device-locking for clear/reconfig

Added the pseudo device-locking using card->shutdown flag to avoid
the crash via clear/reconfig during operations.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 50 insertions, 4 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index a13480fa8e74..5dceee8a113b 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -1445,9 +1445,52 @@ void snd_hda_ctls_clear(struct hda_codec *codec)
         snd_array_free(&codec->mixers);
 }
 
-void snd_hda_codec_reset(struct hda_codec *codec)
+/* pseudo device locking
+ * toggle card->shutdown to allow/disallow the device access (as a hack)
+ */
+static int hda_lock_devices(struct snd_card *card)
 {
-        int i;
+        spin_lock(&card->files_lock);
+        if (card->shutdown) {
+                spin_unlock(&card->files_lock);
+                return -EINVAL;
+        }
+        card->shutdown = 1;
+        spin_unlock(&card->files_lock);
+        return 0;
+}
+
+static void hda_unlock_devices(struct snd_card *card)
+{
+        spin_lock(&card->files_lock);
+        card->shutdown = 0;
+        spin_unlock(&card->files_lock);
+}
+
+int snd_hda_codec_reset(struct hda_codec *codec)
+{
+        struct snd_card *card = codec->bus->card;
+        int i, pcm;
+
+        if (hda_lock_devices(card) < 0)
+                return -EBUSY;
+        /* check whether the codec isn't used by any mixer or PCM streams */
+        if (!list_empty(&card->ctl_files)) {
+                hda_unlock_devices(card);
+                return -EBUSY;
+        }
+        for (pcm = 0; pcm < codec->num_pcms; pcm++) {
+                struct hda_pcm *cpcm = &codec->pcm_info[pcm];
+                if (!cpcm->pcm)
+                        continue;
+                if (cpcm->pcm->streams[0].substream_opened ||
+                    cpcm->pcm->streams[1].substream_opened) {
+                        hda_unlock_devices(card);
+                        return -EBUSY;
+                }
+        }
+
+        /* OK, let it free */
 
 #ifdef CONFIG_SND_HDA_POWER_SAVE
         cancel_delayed_work(&codec->power_work);
@@ -1457,8 +1500,7 @@ void snd_hda_codec_reset(struct hda_codec *codec)
         /* relase PCMs */
         for (i = 0; i < codec->num_pcms; i++) {
                 if (codec->pcm_info[i].pcm) {
-                        snd_device_free(codec->bus->card,
-                                        codec->pcm_info[i].pcm);
+                        snd_device_free(card, codec->pcm_info[i].pcm);
                         clear_bit(codec->pcm_info[i].device,
                                   codec->bus->pcm_dev_bits);
                 }
@@ -1479,6 +1521,10 @@ void snd_hda_codec_reset(struct hda_codec *codec)
         codec->preset = NULL;
         module_put(codec->owner);
         codec->owner = NULL;
+
+        /* allow device access again */
+        hda_unlock_devices(card);
+        return 0;
 }
 #endif /* CONFIG_SND_HDA_RECONFIG */