Commit d61a6d40 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont

LibVLC: hopefully fix media player callback dead lock (fixes #3307)

parent e51d033c
......@@ -70,6 +70,15 @@ static inline void __register_event(libvlc_media_player_t *mp, libvlc_event_type
libvlc_event_manager_register_event_type(mp->p_event_manager, type);
}
/*
* The input lock protects the input and input resource pointer.
* It MUST NOT be used from callbacks.
*
* The object lock protects the reset, namely the media and the player state.
* It can, and usually needs to be taken from callbacks.
* The object lock can be acquired under the input lock... and consequently
* the opposite order is STRICTLY PROHIBITED.
*/
static inline void lock(libvlc_media_player_t *mp)
{
vlc_mutex_lock(&mp->object_lock);
......@@ -80,16 +89,27 @@ static inline void unlock(libvlc_media_player_t *mp)
vlc_mutex_unlock(&mp->object_lock);
}
static inline void lock_input(libvlc_media_player_t *mp)
{
vlc_mutex_lock(&mp->input.lock);
}
static inline void unlock_input(libvlc_media_player_t *mp)
{
vlc_mutex_unlock(&mp->input.lock);
}
/*
* Release the associated input thread.
*
* Object lock is NOT held.
* Input lock is held or instance is being destroyed.
*/
static void release_input_thread( libvlc_media_player_t *p_mi, bool b_input_abort )
{
assert( p_mi );
input_thread_t *p_input_thread = p_mi->p_input_thread;
input_thread_t *p_input_thread = p_mi->input.p_thread;
if( !p_input_thread )
return;
......@@ -105,21 +125,19 @@ static void release_input_thread( libvlc_media_player_t *p_mi, bool b_input_abor
vlc_thread_join( p_input_thread );
assert( p_mi->p_input_resource == NULL );
assert( p_input_thread->b_dead );
/* Store the input resource for future use. */
p_mi->p_input_resource = input_DetachResource( p_input_thread );
assert( p_mi->input.p_resource == NULL );
p_mi->input.p_resource = input_DetachResource( p_input_thread );
p_mi->input.p_thread = NULL;
vlc_object_release( p_input_thread );
p_mi->p_input_thread = NULL;
}
/*
* Retrieve the input thread. Be sure to release the object
* once you are done with it. (libvlc Internal)
*
* Function will lock the object.
*/
input_thread_t *libvlc_get_input_thread( libvlc_media_player_t *p_mi )
{
......@@ -127,13 +145,13 @@ input_thread_t *libvlc_get_input_thread( libvlc_media_player_t *p_mi )
assert( p_mi );
lock(p_mi);
p_input_thread = p_mi->p_input_thread;
lock_input(p_mi);
p_input_thread = p_mi->input.p_thread;
if( p_input_thread )
vlc_object_hold( p_input_thread );
else
libvlc_printerr( "No active input" );
unlock(p_mi);
unlock_input(p_mi);
return p_input_thread;
}
......@@ -312,14 +330,8 @@ static int snapshot_was_taken(vlc_object_t *p_this, char const *psz_cmd,
static input_thread_t *find_input (vlc_object_t *obj)
{
libvlc_media_player_t *mp = (libvlc_media_player_t *)obj;
input_thread_t *p_input;
lock (mp);
p_input = mp->p_input_thread;
if (p_input)
vlc_object_hold (p_input);
unlock (mp);
return p_input;
return libvlc_get_input_thread (mp);
}
/* */
......@@ -414,8 +426,9 @@ libvlc_media_player_new( libvlc_instance_t *instance )
mp->p_md = NULL;
mp->state = libvlc_NothingSpecial;
mp->p_libvlc_instance = instance;
mp->p_input_thread = NULL;
mp->p_input_resource = NULL;
mp->input.p_thread = NULL;
mp->input.p_resource = NULL;
vlc_mutex_init (&mp->input.lock);
mp->i_refcount = 1;
mp->p_event_manager = libvlc_event_manager_new(mp, instance);
if (unlikely(mp->p_event_manager == NULL))
......@@ -492,19 +505,15 @@ static void libvlc_media_player_destroy( libvlc_media_player_t *p_mi )
var_DelCallback( p_mi->p_libvlc,
"snapshot-file", snapshot_was_taken, p_mi );
/* If the input thread hasn't been already deleted it means
* that the owners didn't stop the thread before releasing it. */
assert(!p_mi->p_input_thread);
/* Fallback for those who don't use NDEBUG */
if(p_mi->p_input_thread )
/* No need for lock_input() because no other threads knows us anymore */
if( p_mi->input.p_thread )
release_input_thread(p_mi, true);
if( p_mi->p_input_resource )
if( p_mi->input.p_resource )
{
input_resource_Delete( p_mi->p_input_resource );
p_mi->p_input_resource = NULL;
input_resource_Delete( p_mi->input.p_resource );
p_mi->input.p_resource = NULL;
}
vlc_mutex_destroy( &p_mi->input.lock );
libvlc_event_manager_release( p_mi->p_event_manager );
libvlc_media_release( p_mi->p_md );
......@@ -556,16 +565,18 @@ void libvlc_media_player_set_media(
libvlc_media_player_t *p_mi,
libvlc_media_t *p_md )
{
lock(p_mi);
lock_input(p_mi);
/* FIXME I am not sure if it is a user request or on die(eof/error)
* request here */
release_input_thread( p_mi,
p_mi->p_input_thread &&
!p_mi->p_input_thread->b_eof &&
!p_mi->p_input_thread->b_error );
p_mi->input.p_thread &&
!p_mi->input.p_thread->b_eof &&
!p_mi->input.p_thread->b_error );
set_state( p_mi, libvlc_NothingSpecial, true );
lock( p_mi );
set_state( p_mi, libvlc_NothingSpecial, false );
unlock_input( p_mi );
libvlc_media_release( p_mi->p_md );
......@@ -623,13 +634,14 @@ libvlc_media_player_event_manager( libvlc_media_player_t *p_mi )
**************************************************************************/
int libvlc_media_player_play( libvlc_media_player_t *p_mi )
{
input_thread_t * p_input_thread;
lock_input( p_mi );
if( (p_input_thread = libvlc_get_input_thread( p_mi )) )
input_thread_t *p_input_thread = p_mi->input.p_thread;
if( p_input_thread )
{
/* A thread already exists, send it a play message */
input_Control( p_input_thread, INPUT_SET_STATE, PLAYING_S );
vlc_object_release( p_input_thread );
unlock_input( p_mi );
return 0;
}
......@@ -643,18 +655,17 @@ int libvlc_media_player_play( libvlc_media_player_t *p_mi )
return -1;
}
p_mi->p_input_thread = input_Create( p_mi,
p_mi->p_md->p_input_item, NULL,
p_mi->p_input_resource );
if( !p_mi->p_input_thread )
p_input_thread = input_Create( p_mi, p_mi->p_md->p_input_item, NULL,
p_mi->input.p_resource );
unlock(p_mi);
if( !p_input_thread )
{
unlock(p_mi);
unlock_input(p_mi);
libvlc_printerr( "Not enough memory" );
return -1;
}
p_mi->p_input_resource = NULL;
p_input_thread = p_mi->p_input_thread;
p_mi->input.p_resource = NULL;
var_AddCallback( p_input_thread, "can-seek", input_seekable_changed, p_mi );
var_AddCallback( p_input_thread, "can-pause", input_pausable_changed, p_mi );
......@@ -662,11 +673,16 @@ int libvlc_media_player_play( libvlc_media_player_t *p_mi )
if( input_Start( p_input_thread ) )
{
unlock_input(p_mi);
var_DelCallback( p_input_thread, "intf-event", input_event_changed, p_mi );
var_DelCallback( p_input_thread, "can-pause", input_pausable_changed, p_mi );
var_DelCallback( p_input_thread, "can-seek", input_seekable_changed, p_mi );
vlc_object_release( p_input_thread );
p_mi->p_input_thread = NULL;
libvlc_printerr( "Input initialization failure" );
return -1;
}
unlock(p_mi);
p_mi->input.p_thread = p_input_thread;
unlock_input(p_mi);
return 0;
}
......@@ -711,9 +727,8 @@ void libvlc_media_player_stop( libvlc_media_player_t *p_mi )
{
libvlc_state_t state = libvlc_media_player_get_state( p_mi );
lock(p_mi);
lock_input(p_mi);
release_input_thread( p_mi, true ); /* This will stop the input thread */
unlock(p_mi);
/* Force to go to stopped state, in case we were in Ended, or Error
* state. */
......@@ -726,6 +741,7 @@ void libvlc_media_player_stop( libvlc_media_player_t *p_mi )
event.type = libvlc_MediaPlayerStopped;
libvlc_event_send( p_mi->p_event_manager, &event );
}
unlock_input(p_mi);
}
/**************************************************************************
......
......@@ -40,8 +40,14 @@ struct libvlc_media_player_t
int i_refcount;
vlc_mutex_t object_lock;
input_thread_t * p_input_thread;
input_resource_t * p_input_resource;
struct
{
input_thread_t *p_thread;
input_resource_t *p_resource;
vlc_mutex_t lock;
} input;
struct libvlc_instance_t * p_libvlc_instance; /* Parent instance */
libvlc_media_t * p_md; /* current media descriptor */
libvlc_event_manager_t * p_event_manager;
......
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