V4L/DVB: cx18: Add missing serialization locks to cx18-dvb

Operations that manipulates the state of the encoder or global instance flags
and variables should be serialized.  This adds some serialization locks that
have been missing from cx18-dvb.  Since the DVB part of the CX23418 doesn't
affect the encoder, no one would likely have ever noticed a race in changing
card instance variables.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/media/video/cx18/cx18-dvb.c b/drivers/media/video/cx18/cx18-dvb.c
index 0ad5b63d27fe..0ae2c2e1eab5 100644
--- a/drivers/media/video/cx18/cx18-dvb.c
+++ b/drivers/media/video/cx18/cx18-dvb.c
@@ -260,6 +260,7 @@ static int cx18_dvb_start_feed(struct dvb_demux_feed *feed)
         mutex_lock(&stream->dvb.feedlock);
         if (stream->dvb.feeding++ == 0) {
                 CX18_DEBUG_INFO("Starting Transport DMA\n");
+                mutex_lock(&cx->serialize_lock);
                 set_bit(CX18_F_S_STREAMING, &stream->s_flags);
                 ret = cx18_start_v4l2_encode_stream(stream);
                 if (ret < 0) {
@@ -268,6 +269,7 @@ static int cx18_dvb_start_feed(struct dvb_demux_feed *feed)
                         if (stream->dvb.feeding == 0)
                                 clear_bit(CX18_F_S_STREAMING, &stream->s_flags);
                 }
+                mutex_unlock(&cx->serialize_lock);
         } else
                 ret = 0;
         mutex_unlock(&stream->dvb.feedlock);
@@ -291,7 +293,9 @@ static int cx18_dvb_stop_feed(struct dvb_demux_feed *feed)
                 mutex_lock(&stream->dvb.feedlock);
                 if (--stream->dvb.feeding == 0) {
                         CX18_DEBUG_INFO("Stopping Transport DMA\n");
+                        mutex_lock(&cx->serialize_lock);
                         ret = cx18_stop_v4l2_encode_stream(stream, 0);
+                        mutex_unlock(&cx->serialize_lock);
                 } else
                         ret = 0;
                 mutex_unlock(&stream->dvb.feedlock);