[vlc-devel] [PATCH 3/3] dec: lock p_vout/p_aout when read from the DecoderThread

[Rémi Denis-Courmont]

No. Holding vout/aout gives access to variables and interface controls, nothing else.

Le 17 mai 2018 15:36:55 GMT+03:00, Thomas Guillem <thomas at gllm.fr> a écrit :
>Since these variables can be written from any thread from
>format_update()
>callbacks.
>---
> src/input/decoder.c | 59 +++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 49 insertions(+), 10 deletions(-)
>
>diff --git a/src/input/decoder.c b/src/input/decoder.c
>index 1fdc4fb7ed..e8e4c109ef 100644
>--- a/src/input/decoder.c
>+++ b/src/input/decoder.c
>@@ -103,10 +103,11 @@ struct decoder_owner
>     vlc_cond_t  wait_fifo; /* TODO: merge with wait_acknowledge */
>     vlc_cond_t  wait_timed;
> 
>-    /* -- These variables need locking on write(only) -- */
>+    /* These variables are written from the format_update() callbacks
>threads.
>+     * They need locking when they are read from the DecoderThread
>(use
>+     * dec_get_aout()/dec_get_vout() helpers). */
>     audio_output_t *p_aout;
>-
>-    vout_thread_t   *p_vout;
>+    vout_thread_t  *p_vout;
> 
>     /* -- Theses variables need locking on read *and* write -- */
>     /* Preroll */
>@@ -158,6 +159,24 @@ static inline struct decoder_owner *dec_get_owner(
>decoder_t *p_dec )
>     return container_of( p_dec, struct decoder_owner, dec );
> }
> 
>+static audio_output_t *dec_get_aout( decoder_t *p_dec )
>+{
>+    struct decoder_owner *p_owner = dec_get_owner( p_dec );
>+    vlc_mutex_lock( &p_owner->lock );
>+    audio_output_t *p_aout = p_owner->p_aout ? vlc_object_hold(
>p_owner->p_aout ) : NULL;
>+    vlc_mutex_unlock( &p_owner->lock );
>+    return p_aout;
>+}
>+
>+static vout_thread_t *dec_get_vout( decoder_t *p_dec )
>+{
>+    struct decoder_owner *p_owner = dec_get_owner( p_dec );
>+    vlc_mutex_lock( &p_owner->lock );
>+    vout_thread_t *p_vout = p_owner->p_vout ? vlc_object_hold(
>p_owner->p_vout ) : NULL;
>+    vlc_mutex_unlock( &p_owner->lock );
>+    return p_vout;
>+}
>+
> /**
>  * Load a decoder module
>  */
>@@ -238,15 +257,17 @@ static int ReloadDecoder( decoder_t *p_dec, bool
>b_packetizer,
>     if( reload == RELOAD_DECODER_AOUT )
>     {
>         assert( p_owner->fmt.i_cat == AUDIO_ES );
>-        audio_output_t *p_aout = p_owner->p_aout;
> 
>         vlc_mutex_lock( &p_owner->lock );
>+        audio_output_t *p_aout = p_owner->p_aout ? vlc_object_hold(
>p_owner->p_aout ) : NULL;
>         p_owner->p_aout = NULL;
>         vlc_mutex_unlock( &p_owner->lock );
>+
>         if( p_aout )
>         {
>             aout_DecDelete( p_aout );
>             input_resource_PutAout( p_owner->p_resource, p_aout );
>+            vlc_object_release( p_aout );
>         }
>     }
> 
>@@ -1538,13 +1559,25 @@ static void *DecoderThread( void *p_data )
>             switch( p_dec->fmt_out.i_cat )
>             {
>                 case VIDEO_ES:
>-                    if( p_owner->p_vout != NULL )
>-                        vout_ChangePause( p_owner->p_vout, paused,
>date );
>+                {
>+                    vout_thread_t *p_vout = dec_get_vout( p_dec );
>+                    if( p_vout != NULL )
>+                    {
>+                        vout_ChangePause( p_vout, paused, date );
>+                        vlc_object_release( p_vout );
>+                    }
>                     break;
>+                }
>                 case AUDIO_ES:
>-                    if( p_owner->p_aout != NULL )
>-                        aout_DecChangePause( p_owner->p_aout, paused,
>date );
>+                {
>+                    audio_output_t *p_aout = dec_get_aout( p_dec );
>+                    if( p_aout != NULL )
>+                    {
>+                        aout_DecChangePause( p_aout, paused, date );
>+                        vlc_object_release( p_aout );
>+                    }
>                     break;
>+                }
>                 case SPU_ES:
>                     break;
>                 default:
>@@ -1569,9 +1602,15 @@ static void *DecoderThread( void *p_data )
>                 case VIDEO_ES:
>                     break;
>                 case AUDIO_ES:
>-                    if( p_owner->p_aout != NULL )
>-                        aout_DecChangeRate( p_owner->p_aout, rate );
>+                {
>+                    audio_output_t *p_aout = dec_get_aout( p_dec );
>+                    if( p_aout != NULL )
>+                    {
>+                        aout_DecChangeRate( p_aout, rate );
>+                        vlc_object_release( p_aout );
>+                    }
>                     break;
>+                }
>                 case SPU_ES:
>                     break;
>                 default:
>-- 
>2.17.0
>
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