ALSA: isight: fix isight_pcm_abort() crashes

Fix crashes in isight_pcm_abort() that happen when the driver tries to
access isight->pcm->runtime which does not exist when the device is not
open.  Introduce a new field pcm_active to track this state.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/isight.c b/sound/firewire/isight.c
index a6f19f5..0230605 100644 (file)
--- a/sound/firewire/isight.c
+++ b/sound/firewire/isight.c
@@ -56,6 +56,7 @@ struct isight {
        struct iso_packets_buffer buffer;
        struct fw_iso_resources resources;
        struct fw_iso_context *context;
+       bool pcm_active;
        bool pcm_running;
        bool first_packet;
        int packet_index;
@@ -131,10 +132,12 @@ static void isight_pcm_abort(struct isight *isight)
 {
        unsigned long flags;
 
-       snd_pcm_stream_lock_irqsave(isight->pcm, flags);
-       if (snd_pcm_running(isight->pcm))
-               snd_pcm_stop(isight->pcm, SNDRV_PCM_STATE_XRUN);
-       snd_pcm_stream_unlock_irqrestore(isight->pcm, flags);
+       if (ACCESS_ONCE(isight->pcm_active)) {
+               snd_pcm_stream_lock_irqsave(isight->pcm, flags);
+               if (snd_pcm_running(isight->pcm))
+                       snd_pcm_stop(isight->pcm, SNDRV_PCM_STATE_XRUN);
+               snd_pcm_stream_unlock_irqrestore(isight->pcm, flags);
+       }
 }
 
 static void isight_dropped_samples(struct isight *isight, unsigned int total)
@@ -295,8 +298,17 @@ static int isight_close(struct snd_pcm_substream *substream)
 static int isight_hw_params(struct snd_pcm_substream *substream,
                            struct snd_pcm_hw_params *hw_params)
 {
-       return snd_pcm_lib_alloc_vmalloc_buffer(substream,
-                                               params_buffer_bytes(hw_params));
+       struct isight *isight = substream->private_data;
+       int err;
+
+       err = snd_pcm_lib_alloc_vmalloc_buffer(substream,
+                                              params_buffer_bytes(hw_params));
+       if (err < 0)
+               return err;
+
+       ACCESS_ONCE(isight->pcm_active) = true;
+
+       return 0;
 }
 
 static void isight_stop_streaming(struct isight *isight)
@@ -322,6 +334,8 @@ static int isight_hw_free(struct snd_pcm_substream *substream)
 {
        struct isight *isight = substream->private_data;
 
+       ACCESS_ONCE(isight->pcm_active) = false;
+
        mutex_lock(&isight->mutex);
        isight_stop_streaming(isight);
        mutex_unlock(&isight->mutex);