On 02/04/2016 02:18 AM, Mauro Carvalho Chehab wrote: > Em Wed, 03 Feb 2016 21:03:38 -0700 > Shuah Khan <[email protected]> escreveu: > >> Add non-locking __media_entity_pipeline_start/stop() interfaces >> to be called from code paths that hold the graph_mutex. For this >> change, the media_entity_pipeline_start() routine is renamed to >> __media_entity_pipeline_start() minus the graph_mutex lock and >> unlock. media_entity_pipeline_start() now calls the non-locking >> __media_entity_pipeline_start() holding the graph_lock. The stop >> interface, media_entity_pipeline_stop() routine is renamed to >> __media_entity_pipeline_stop() minus the graph_mutex lock and >> unlock. media_entity_pipeline_stop() now calls the non-locking >> __media_entity_pipeline_stop() holding the graph_lock. > > Please write a better patch descriptions. The above could easily > be split into 3 or 4 paragraphs, with would make it easier to > read. >
Removed linux-api from cc list ok - I updated several changelogs based on your earlier comments and this one slipped by. -- Shuah > Also, too much details, written on a spaghetti style;) > > It is obvious by anyone that looked at the patch that > "media_entity_pipeline_start() routine is renamed to > __media_entity_pipeline_start() minus the graph_mutex lock and > unlock." > > I read exactly the same thing at the C code, *and* at the > subject of the e-mail. Patch subject/description should tell > what, why and how (but you should not repeat what can easily > be inferred from looking at the diff). > > I would describe it as: > > Currently, media pipeline graph traversal routines take > the graph_mutex lock. > > While this works for the current code, we'll need > unlocked versions of them because > (some explanation *why* you need it, with is the main > thing that should be at the description). > > So, add non-locking media_entity_pipeline_start/stop() > variations. > >> >> Signed-off-by: Shuah Khan <[email protected]> >> --- >> drivers/media/media-entity.c | 34 ++++++++++++++++++++++++---------- >> include/media/media-entity.h | 12 ++++++++++++ >> 2 files changed, 36 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c >> index 9b4d712..b78e4c2 100644 >> --- a/drivers/media/media-entity.c >> +++ b/drivers/media/media-entity.c >> @@ -365,8 +365,8 @@ EXPORT_SYMBOL_GPL(media_entity_graph_walk_next); >> * Pipeline management >> */ >> >> -__must_check int media_entity_pipeline_start(struct media_entity *entity, >> - struct media_pipeline *pipe) >> +__must_check int __media_entity_pipeline_start(struct media_entity *entity, >> + struct media_pipeline *pipe) >> { >> struct media_device *mdev = entity->graph_obj.mdev; >> struct media_entity_graph *graph = &pipe->graph; >> @@ -374,8 +374,6 @@ __must_check int media_entity_pipeline_start(struct >> media_entity *entity, >> struct media_link *link; >> int ret; >> >> - mutex_lock(&mdev->graph_mutex); >> - >> if (!pipe->streaming_count++) { >> ret = media_entity_graph_walk_init(&pipe->graph, mdev); >> if (ret) >> @@ -456,8 +454,6 @@ __must_check int media_entity_pipeline_start(struct >> media_entity *entity, >> } >> } >> >> - mutex_unlock(&mdev->graph_mutex); >> - >> return 0; >> >> error: >> @@ -487,19 +483,28 @@ error_graph_walk_start: >> if (!--pipe->streaming_count) >> media_entity_graph_walk_cleanup(graph); >> >> - mutex_unlock(&mdev->graph_mutex); >> + return ret; >> +} >> +EXPORT_SYMBOL_GPL(__media_entity_pipeline_start); >> >> +__must_check int media_entity_pipeline_start(struct media_entity *entity, >> + struct media_pipeline *pipe) >> +{ >> + struct media_device *mdev = entity->graph_obj.mdev; >> + int ret; >> + >> + mutex_lock(&mdev->graph_mutex); >> + ret = __media_entity_pipeline_start(entity, pipe); >> + mutex_unlock(&mdev->graph_mutex); >> return ret; >> } >> EXPORT_SYMBOL_GPL(media_entity_pipeline_start); >> >> -void media_entity_pipeline_stop(struct media_entity *entity) >> +void __media_entity_pipeline_stop(struct media_entity *entity) >> { >> - struct media_device *mdev = entity->graph_obj.mdev; >> struct media_entity_graph *graph = &entity->pipe->graph; >> struct media_pipeline *pipe = entity->pipe; >> >> - mutex_lock(&mdev->graph_mutex); >> >> WARN_ON(!pipe->streaming_count); >> media_entity_graph_walk_start(graph, entity); >> @@ -516,6 +521,15 @@ void media_entity_pipeline_stop(struct media_entity >> *entity) >> if (!--pipe->streaming_count) >> media_entity_graph_walk_cleanup(graph); >> >> +} >> +EXPORT_SYMBOL_GPL(__media_entity_pipeline_stop); >> + >> +void media_entity_pipeline_stop(struct media_entity *entity) >> +{ >> + struct media_device *mdev = entity->graph_obj.mdev; >> + >> + mutex_lock(&mdev->graph_mutex); >> + __media_entity_pipeline_stop(entity); >> mutex_unlock(&mdev->graph_mutex); >> } >> EXPORT_SYMBOL_GPL(media_entity_pipeline_stop); >> diff --git a/include/media/media-entity.h b/include/media/media-entity.h >> index fe485d3..c7583db 100644 >> --- a/include/media/media-entity.h >> +++ b/include/media/media-entity.h >> @@ -832,6 +832,12 @@ media_entity_graph_walk_next(struct media_entity_graph >> *graph); >> */ >> __must_check int media_entity_pipeline_start(struct media_entity *entity, >> struct media_pipeline *pipe); >> +/** >> + * non-locking __media_entity_pipeline_start() can be called from >> + * code paths that hold the graph_mutex >> + */ >> +__must_check int __media_entity_pipeline_start(struct media_entity *entity, >> + struct media_pipeline *pipe); >> >> /** >> * media_entity_pipeline_stop - Mark a pipeline as not streaming >> @@ -848,6 +854,12 @@ __must_check int media_entity_pipeline_start(struct >> media_entity *entity, >> void media_entity_pipeline_stop(struct media_entity *entity); >> >> /** >> + * non-locking __media_entity_pipeline_stop() can be called from >> + * code paths that hold the graph_mutex >> + */ >> +void __media_entity_pipeline_stop(struct media_entity *entity); >> + >> +/** >> * media_devnode_create() - creates and initializes a device node interface >> * >> * @mdev: pointer to struct &media_device -- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) [email protected] | (970) 217-8978
