[vlc-devel] [vlc-commits] picture_pool: fix race condition

[Thomas Guillem]

On Wed, Oct 29, 2014, at 20:27, Rémi Denis-Courmont wrote:
> vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Tue Oct 28
> 21:30:02 2014 +0200| [9e99ef07827bb2a1796770ad0b12b028b8643ede] |
> committer: Rémi Denis-Courmont
> 
> picture_pool: fix race condition
> 
> This makes picture_pool_Get() reentrant.
> 
> > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=9e99ef07827bb2a1796770ad0b12b028b8643ede
> ---
> 
>  src/misc/picture_pool.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/src/misc/picture_pool.c b/src/misc/picture_pool.c
> index cfaa541..2a0f677 100644
> --- a/src/misc/picture_pool.c
> +++ b/src/misc/picture_pool.c
> @@ -272,7 +272,9 @@ picture_t *picture_pool_Get(picture_pool_t *pool)
>              continue;
>  
>          picture_t *picture = pool->picture[i];
> -        if (atomic_load(&picture->gc.refcount) > 0)
> +        uintptr_t refs = 0;
> +
> +        if (!atomic_compare_exchange_strong(&picture->gc.refcount,
> &refs, 1))
>              continue;
>  
>          if (pool->pic_lock != NULL && pool->pic_lock(picture) != 0)
> @@ -281,7 +283,6 @@ picture_t *picture_pool_Get(picture_pool_t *pool)
>          /* */
>          picture->p_next = NULL;
>          picture->gc.p_sys->tick = pool->tick++;
> -        picture_Hold(picture);
>          return picture;
>      }
>      return NULL;
> 

This patch break software rendering on android: no picture rendered.

log: "yuv_rgb_neon filter: can't get output picture"

filter_NewPicture() fails from modules/arm_neon/yuv_rgb.c:127

I tried to debug it but I got lost. 

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