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>

diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c
index 069d847ba887c39e2f1f83eafdf7c06a07b838a7..0c733c66a44150d7abd6afdea0acbbd760fe385b 100644 (file)
--- 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 e2eca0b1fe7cfad6dc1215aa6d2bd1247497b93e..a2c1fd5d2f67b05b5b25da04cf6a8dc0d7e8da49 100644 (file)
--- 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);