[vlc-devel] [PATCH] DXVA2: lock the buffer pool when getting/releasing a buffer

[Steve Lhomme]

On Fri, Apr 3, 2015 at 1:15 PM, Steve Lhomme <robux4 at videolabs.io> wrote:
> On Fri, Apr 3, 2015 at 1:12 PM, Steve Lhomme <robUx4 at videolabs.io> wrote:
>> in frame threading mode, the buffers can be requested from different threads, resulting in a race condition
>> only needed if thread_safe_callbacks is set in avcodec
>
> The same thing might be needed in VAAPI as well.

I spoke too fast, the lock is already there, just not conditional on
the thread_safe_callbacks flag.
http://git.videolan.org/?p=vlc.git;a=blob;f=modules/codec/avcodec/vaapi.c;h=2271f9ea625dcd7ac0aad8788dc2cf1f0d9d5f1f;hb=HEAD#l359

>> --
>> replaces the previous patch with the same name
>> ---
>>  modules/codec/avcodec/dxva2.c | 24 ++++++++++++++++++++++++
>>  1 file changed, 24 insertions(+)
>>
>> diff --git a/modules/codec/avcodec/dxva2.c b/modules/codec/avcodec/dxva2.c
>> index 3f3707e..e3941ca 100644
>> --- a/modules/codec/avcodec/dxva2.c
>> +++ b/modules/codec/avcodec/dxva2.c
>> @@ -263,6 +263,7 @@ typedef struct {
>>      LPDIRECT3DSURFACE9 d3d;
>>      int                refcount;
>>      unsigned int       order;
>> +    vlc_va_sys_t       *sys;
>>  } vlc_va_surface_t;
>>
>>  #define VA_DXVA2_MAX_SURFACE_COUNT (64)
>> @@ -272,6 +273,9 @@ struct vlc_va_sys_t
>>      int          width;
>>      int          height;
>>
>> +    bool            b_thread_safe;
>> +    vlc_mutex_t     surface_lock;
>> +
>>      /* DLL */
>>      HINSTANCE             hd3d9_dll;
>>      HINSTANCE             hdxva2_dll;
>> @@ -466,6 +470,9 @@ static int Get(vlc_va_t *va, void **opaque, uint8_t **data)
>>          return VLC_EGENERIC;
>>      }
>>
>> +    if ( sys->b_thread_safe )
>> +        vlc_mutex_lock( &sys->surface_lock );
>> +
>>      /* Grab an unused surface, in case none are, try the oldest
>>       * XXX using the oldest is a workaround in case a problem happens with libavcodec */
>>      unsigned i, old;
>> @@ -487,6 +494,10 @@ static int Get(vlc_va_t *va, void **opaque, uint8_t **data)
>>      surface->order = sys->surface_order++;
>>      *data = (void *)surface->d3d;
>>      *opaque = surface;
>> +
>> +    if ( sys->b_thread_safe )
>> +        vlc_mutex_unlock( &sys->surface_lock );
>> +
>>      return VLC_SUCCESS;
>>  }
>>
>> @@ -494,8 +505,14 @@ static void Release(void *opaque, uint8_t *data)
>>  {
>>      vlc_va_surface_t *surface = opaque;
>>
>> +    if ( surface->sys->b_thread_safe )
>> +        vlc_mutex_lock( &surface->sys->surface_lock );
>> +
>>      surface->refcount--;
>>      (void) data;
>> +
>> +    if ( surface->sys->b_thread_safe )
>> +        vlc_mutex_unlock( &surface->sys->surface_lock );
>>  }
>>
>>  static void Close(vlc_va_t *va, AVCodecContext *ctx)
>> @@ -513,6 +530,8 @@ static void Close(vlc_va_t *va, AVCodecContext *ctx)
>>          FreeLibrary(sys->hdxva2_dll);
>>      if (sys->hd3d9_dll)
>>          FreeLibrary(sys->hd3d9_dll);
>> +    if ( sys->b_thread_safe )
>> +        vlc_mutex_destroy( &sys->surface_lock );
>>
>>      free((char *)va->description);
>>      free(sys);
>> @@ -528,6 +547,10 @@ static int Open(vlc_va_t *va, AVCodecContext *ctx, const es_format_t *fmt)
>>      sys->codec_id = ctx->codec_id;
>>      (void) fmt;
>>
>> +    sys->b_thread_safe = ctx->thread_safe_callbacks;
>> +    if ( sys->b_thread_safe )
>> +        vlc_mutex_init( &sys->surface_lock );
>> +
>>      /* Load dll*/
>>      sys->hd3d9_dll = LoadLibrary(TEXT("D3D9.DLL"));
>>      if (!sys->hd3d9_dll) {
>> @@ -936,6 +959,7 @@ static int DxCreateVideoDecoder(vlc_va_t *va, int codec_id,
>>          surface->d3d = sys->hw_surface[i];
>>          surface->refcount = 0;
>>          surface->order = 0;
>> +        surface->sys = sys;
>>      }
>>      msg_Dbg(va, "IDirectXVideoAccelerationService_CreateSurface succeed with %d surfaces (%dx%d)",
>>              sys->surface_count, fmt->i_width, fmt->i_height);
>> --
>> 2.3.2
>>
>> _______________________________________________
>> vlc-devel mailing list
>> To unsubscribe or modify your subscription options:
>> https://mailman.videolan.org/listinfo/vlc-devel
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel