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

[Eero Tamminen]

Hi,

I tested this on KBL GT2.  Compiz crashes during 3h test run dropped 
from 30 to none.  There were couple of percent changes in few synthetic 
tests, but I think that's just because Compiz is now running properly.

-> looks good!


	- Eero

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


On 06.04.2018 11:12, 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"
> 
> 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 | 7 +++++--
>   src/loader/loader_dri3_helper.h | 1 +
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_helper.c
> index fe17df1..5f9cc42 100644
> --- a/src/loader/loader_dri3_helper.c
> +++ b/src/loader/loader_dri3_helper.c
> @@ -422,7 +422,7 @@ dri3_handle_present_event(struct loader_dri3_drawable *draw,
>               buf->busy = 0;
>   
>            if (buf && draw->cur_blit_source != b && !buf->busy &&
> -             (buf->reallocate ||
> +             ((buf->reallocate && !buf->in_use_to_destroy) ||
>                (draw->num_back <= b && b < LOADER_DRI3_MAX_BACK))) {
>               dri3_free_render_buffer(draw, buf);
>               draw->buffers[b] = NULL;
> @@ -1688,6 +1688,7 @@ dri3_get_buffer(__DRIdrawable *driDrawable,
>              (buffer_type == loader_dri3_buffer_front && draw->have_fake_front))
>             && buffer) {
>   
> +         buffer->in_use_to_destroy = 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];
>   
> diff --git a/src/loader/loader_dri3_helper.h b/src/loader/loader_dri3_helper.h
> index 7e3d829..9232d61 100644
> --- a/src/loader/loader_dri3_helper.h
> +++ b/src/loader/loader_dri3_helper.h
> @@ -62,6 +62,7 @@ struct loader_dri3_buffer {
>      bool         busy;           /* Set on swap, cleared on IdleNotify */
>      bool         own_pixmap;     /* We allocated the pixmap ID, free on destroy */
>      bool         reallocate;     /* Buffer should be reallocated and not reused */
> +   bool         in_use_to_destroy;     /* Buffer is in use and will be destroyed soon */
>   
>      uint32_t     num_planes;
>      uint32_t     size;
>