V4L/DVB: cx18: Add missing serialization locking to cx18-alsa

File operations that manipulate the state of the encoder, or video or audio
subdevices or some of the stream flags need to be serialized.  Add the
serilization locks to cx18-alsa in a manner consistent with the locking for
the v4l2 file operations.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-alsa-pcm.c

@@ -156,12 +156,15 @@ static int snd_cx18_pcm_capture_open(struct snd_pcm_substream *substream)
 	int ret;
 
 	/* Instruct the cx18 to start sending packets */
+	snd_cx18_lock(cxsc);
 	s = &cx->streams[CX18_ENC_STREAM_TYPE_PCM];
 
 	/* Allocate memory */
 	item = kmalloc(sizeof(struct cx18_open_id), GFP_KERNEL);
-	if (NULL == item)
+	if (NULL == item) {
+		snd_cx18_unlock(cxsc);
 		return -ENOMEM;
+	}
 
 	item->cx = cx;
 	item->type = s->type;
@@ -171,12 +174,14 @@ static int snd_cx18_pcm_capture_open(struct snd_pcm_substream *substream)
 	if (cx18_claim_stream(item, item->type)) {
 		/* No, it's already in use */
 		kfree(item);
+		snd_cx18_unlock(cxsc);
 		return -EBUSY;
 	}
 
 	if (test_bit(CX18_F_S_STREAMOFF, &s->s_flags) ||
 	    test_and_set_bit(CX18_F_S_STREAMING, &s->s_flags)) {
 		/* We're already streaming.  No additional action required */
+		snd_cx18_unlock(cxsc);
 		return 0;
 	}
 
@@ -191,6 +196,7 @@ static int snd_cx18_pcm_capture_open(struct snd_pcm_substream *substream)
 	/* Not currently streaming, so start it up */
 	set_bit(CX18_F_S_STREAMING, &s->s_flags);
 	ret = cx18_start_v4l2_encode_stream(s);
+	snd_cx18_unlock(cxsc);
 
 	return 0;
 }
@@ -204,6 +210,7 @@ static int snd_cx18_pcm_capture_close(struct snd_pcm_substream *substream)
 	int ret;
 
 	/* Instruct the cx18 to stop sending packets */
+	snd_cx18_lock(cxsc);
 	s = &cx->streams[CX18_ENC_STREAM_TYPE_PCM];
 	ret = cx18_stop_v4l2_encode_stream(s, 0);
 	clear_bit(CX18_F_S_STREAMING, &s->s_flags);
@@ -211,6 +218,7 @@ static int snd_cx18_pcm_capture_close(struct snd_pcm_substream *substream)
 	cx18_release_stream(s);
 
 	cx->pcm_announce_callback = NULL;
+	snd_cx18_unlock(cxsc);
 
 	return 0;
 }