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>

2 files changed, 19 insertions, 13 deletions

diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c
index 069d847ba887..0c733c66a441 100644
--- a/drivers/media/dvb/dvb-core/dmxdev.c
+++ b/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;
 }
diff --git a/drivers/media/dvb/dvb-core/dvb_demux.c b/drivers/media/dvb/dvb-core/dvb_demux.c
index e2eca0b1fe7c..a2c1fd5d2f67 100644
--- a/drivers/media/dvb/dvb-core/dvb_demux.c
+++ b/drivers/media/dvb/dvb-core/dvb_demux.c
@@ -399,7 +399,9 @@ 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)
@@ -407,16 +409,17 @@ void dvb_dmx_swfilter_packets(struct dvb_demux *demux, const u8 *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);