sdl/consumer_sdl.c: use mutex when changing sdl_screen

Fixes Coverity CID 709357 and 709358: Data race condition (MISSING_LOCK)

Locking "mlt_sdl_mutex".
235                        pthread_mutex_lock( &mlt_sdl_mutex );
consumer_sdl_s.sdl_screen is being accessed with lock "mlt_sdl_mutex" held.
236                        this->sdl_screen = SDL_GetVideoSurface( );
237                        pthread_mutex_unlock( &mlt_sdl_mutex );
...
Locking "mlt_sdl_mutex".
269                        pthread_mutex_lock( &mlt_sdl_mutex );
consumer_sdl_s.sdl_screen is being accessed with lock "mlt_sdl_mutex" held.
270                        this->sdl_screen = SDL_SetVideoMode( this->window_width, this->window_height, 0, this->sdl_flags );
271                        pthread_mutex_unlock( &mlt_sdl_mutex );
...
Accessing variable "this->sdl_screen" (consumer_sdl_s.sdl_screen) requires the mlt_sdl_mutex lock.
315                this->sdl_screen = NULL;
...
Locking "mlt_sdl_mutex".
573                        pthread_mutex_lock( &mlt_sdl_mutex );
consumer_sdl_s.sdl_screen is being accessed with lock "mlt_sdl_mutex" held.
574                        this->sdl_screen = SDL_SetVideoMode( this->window_width, this->window_height, this->bpp, this->sdl_flags );
575                        if ( consumer_get_dimensions( &this->window_width, &this->window_height ) )
consumer_sdl_s.sdl_screen is being accessed with lock "mlt_sdl_mutex" held.
576                                this->sdl_screen = SDL_SetVideoMode( this->window_width, this->window_height, this->bpp, this->sdl_flags );
577                        pthread_mutex_unlock( &mlt_sdl_mutex );

diff --git a/src/modules/sdl/consumer_sdl.c b/src/modules/sdl/consumer_sdl.c
index 4c9489cb6ba2ec71bd932bfd0af7cd6406c9c159..ac203282654d20c91acaa723e3d891e6e27b2f26 100644 (file)
--- a/src/modules/sdl/consumer_sdl.c
+++ b/src/modules/sdl/consumer_sdl.c
@@ -312,7 +312,9 @@ int consumer_stop( mlt_consumer parent )
                        pthread_mutex_unlock( &mlt_sdl_mutex );
                }
 
+               pthread_mutex_lock( &mlt_sdl_mutex );
                this->sdl_screen = NULL;
+               pthread_mutex_unlock( &mlt_sdl_mutex );
        }
 
        return 0;
@@ -868,7 +870,9 @@ static void *consumer_thread( void *arg )
        while( mlt_deque_count( this->queue ) )
                mlt_frame_close( mlt_deque_pop_back( this->queue ) );
 
+       pthread_mutex_lock( &mlt_sdl_mutex );
        this->sdl_screen = NULL;
+       pthread_mutex_unlock( &mlt_sdl_mutex );
        this->audio_avail = 0;
 
        return NULL;