[Mesa-dev] [PATCH v2] dri3: Prevent multiple freeing of buffers.

[Eero Tamminen]

Hi,

Tested on KBL GT2.

Before the patch, there are few dozen compiz segfaults during ~3 hours 
of testing.  With the patched version there are no segfaults.

Tested-by: Eero Tamminen <eero.t.tamminen at intel.com>

	- Eero

On 10.04.2018 10:44, Sergii Romantsov wrote:
> Commit 3160cb86aa92 adds optimization with flag 'reallocate'.
> Processing of flag causes buffers freeing while pointer
> is still hold in caller stack and than again used to be freed.
> 
> Fixes: 3160cb86aa92 "egl/x11: Re-allocate buffers if format is suboptimal"
> 
> v2:
>   used flag 'busy' instead of introducing new one.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105906
> Signed-off-by: Sergii Romantsov <sergii.romantsov at globallogic.com>
> Tested-by: Andriy Khulap <andriy.khulap at globallogic.com>
> ---
>   src/loader/loader_dri3_helper.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_helper.c
> index fe17df1..a934db1 100644
> --- a/src/loader/loader_dri3_helper.c
> +++ b/src/loader/loader_dri3_helper.c
> @@ -1688,6 +1688,7 @@ dri3_get_buffer(__DRIdrawable *driDrawable,
>              (buffer_type == loader_dri3_buffer_front && draw->have_fake_front))
>             && buffer) {
>   
> +         buffer->busy = true;
>            /* Fill the new buffer with data from an old buffer */
>            dri3_fence_await(draw->conn, draw, buffer);
>            if (!loader_dri3_blit_image(draw,
> @@ -1731,6 +1732,7 @@ dri3_get_buffer(__DRIdrawable *driDrawable,
>         draw->buffers[buf_id] = buffer;
>      }
>      dri3_fence_await(draw->conn, draw, buffer);
> +   buffer = draw->buffers[buf_id];
>   
>      /*
>       * Do we need to preserve the content of a previous buffer?
> @@ -1744,7 +1746,8 @@ dri3_get_buffer(__DRIdrawable *driDrawable,
>      if (buffer_type == loader_dri3_buffer_back &&
>          draw->cur_blit_source != -1 &&
>          draw->buffers[draw->cur_blit_source] &&
> -       buffer != draw->buffers[draw->cur_blit_source]) {
> +       buffer != draw->buffers[draw->cur_blit_source] &&
> +       buffer != NULL) {
>   
>         struct loader_dri3_buffer *source = draw->buffers[draw->cur_blit_source];
>   
>