V4L/DVB (9029): Fix deadlock in demux code

The functions dvb_dmxdev_section_callback, dvb_dmxdev_ts_callback,
dvb_dmx_swfilter_packet, dvb_dmx_swfilter_packets, dvb_dmx_swfilter and
dvb_dmx_swfilter_204 may be called from both interrupt and process
context. Therefore they need to be protected by spin_lock_irqsave()
instead of spin_lock().

This fixes a deadlock discovered by lockdep.

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-core/dmxdev.c

@@ -364,15 +364,16 @@ static int dvb_dmxdev_section_callback(const u8 *buffer1, size_t buffer1_len,
 				       enum dmx_success success)
 {
 	struct dmxdev_filter *dmxdevfilter = filter->priv;
+	unsigned long flags;
 	int ret;
 
 	if (dmxdevfilter->buffer.error) {
 		wake_up(&dmxdevfilter->buffer.queue);
 		return 0;
 	}
-	spin_lock(&dmxdevfilter->dev->lock);
+	spin_lock_irqsave(&dmxdevfilter->dev->lock, flags);
 	if (dmxdevfilter->state != DMXDEV_STATE_GO) {
-		spin_unlock(&dmxdevfilter->dev->lock);
+		spin_unlock_irqrestore(&dmxdevfilter->dev->lock, flags);
 		return 0;
 	}
 	del_timer(&dmxdevfilter->timer);
@@ -391,7 +392,7 @@ static int dvb_dmxdev_section_callback(const u8 *buffer1, size_t buffer1_len,
 	}
 	if (dmxdevfilter->params.sec.flags & DMX_ONESHOT)
 		dmxdevfilter->state = DMXDEV_STATE_DONE;
-	spin_unlock(&dmxdevfilter->dev->lock);
+	spin_unlock_irqrestore(&dmxdevfilter->dev->lock, flags);
 	wake_up(&dmxdevfilter->buffer.queue);
 	return 0;
 }
@@ -403,11 +404,12 @@ static int dvb_dmxdev_ts_callback(const u8 *buffer1, size_t buffer1_len,
 {
 	struct dmxdev_filter *dmxdevfilter = feed->priv;
 	struct dvb_ringbuffer *buffer;
+	unsigned long flags;
 	int ret;
 
-	spin_lock(&dmxdevfilter->dev->lock);
+	spin_lock_irqsave(&dmxdevfilter->dev->lock, flags);
 	if (dmxdevfilter->params.pes.output == DMX_OUT_DECODER) {
-		spin_unlock(&dmxdevfilter->dev->lock);
+		spin_unlock_irqrestore(&dmxdevfilter->dev->lock, flags);
 		return 0;
 	}
 
@@ -417,7 +419,7 @@ static int dvb_dmxdev_ts_callback(const u8 *buffer1, size_t buffer1_len,
 	else
 		buffer = &dmxdevfilter->dev->dvr_buffer;
 	if (buffer->error) {
-		spin_unlock(&dmxdevfilter->dev->lock);
+		spin_unlock_irqrestore(&dmxdevfilter->dev->lock, flags);
 		wake_up(&buffer->queue);
 		return 0;
 	}
@@ -428,7 +430,7 @@ static int dvb_dmxdev_ts_callback(const u8 *buffer1, size_t buffer1_len,
 		dvb_ringbuffer_flush(buffer);
 		buffer->error = ret;
 	}
-	spin_unlock(&dmxdevfilter->dev->lock);
+	spin_unlock_irqrestore(&dmxdevfilter->dev->lock, flags);
 	wake_up(&buffer->queue);
 	return 0;
 }

drivers/media/dvb/dvb-core/dvb_demux.c

@@ -399,24 +399,27 @@ static void dvb_dmx_swfilter_packet(struct dvb_demux *demux, const u8 *buf)
 void dvb_dmx_swfilter_packets(struct dvb_demux *demux, const u8 *buf,
 			      size_t count)
 {
-	spin_lock(&demux->lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&demux->lock, flags);
 
 	while (count--) {
 		if (buf[0] == 0x47)
 			dvb_dmx_swfilter_packet(demux, buf);
 		buf += 188;
 	}
 
-	spin_unlock(&demux->lock);
+	spin_unlock_irqrestore(&demux->lock, flags);
 }
 
 EXPORT_SYMBOL(dvb_dmx_swfilter_packets);
 
 void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count)
 {
+	unsigned long flags;
 	int p = 0, i, j;
 
-	spin_lock(&demux->lock);
+	spin_lock_irqsave(&demux->lock, flags);
 
 	if (demux->tsbufp) {
 		i = demux->tsbufp;
@@ -449,17 +452,18 @@ void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count)
 	}
 
 bailout:
-	spin_unlock(&demux->lock);
+	spin_unlock_irqrestore(&demux->lock, flags);
 }
 
 EXPORT_SYMBOL(dvb_dmx_swfilter);
 
 void dvb_dmx_swfilter_204(struct dvb_demux *demux, const u8 *buf, size_t count)
 {
+	unsigned long flags;
 	int p = 0, i, j;
 	u8 tmppack[188];
 
-	spin_lock(&demux->lock);
+	spin_lock_irqsave(&demux->lock, flags);
 
 	if (demux->tsbufp) {
 		i = demux->tsbufp;
@@ -500,7 +504,7 @@ void dvb_dmx_swfilter_204(struct dvb_demux *demux, const u8 *buf, size_t count)
 	}
 
 bailout:
-	spin_unlock(&demux->lock);
+	spin_unlock_irqrestore(&demux->lock, flags);
 }
 
 EXPORT_SYMBOL(dvb_dmx_swfilter_204);