Re: [PATCH x11spice v2] Use separate buffer for primary surface to fix graphical corruption

[Jeremy White <jwhite@xxxxxxxxxxxxxxx>]

On 8/6/19 11:02 AM, Brendan Shanks wrote:
> The 'display->fullscreen' SHM segment was previously being used for both
> x11spice's internal change scanning and as the spice primary surface.
> I don't think spice wants anything else writing to the primary surface,
> and this caused sporadic test failures and graphical corruption.
>
> Create a separate SHM segment 'display->primary' and use it only for the
> primary surface.
>
> Signed-off-by: Brendan Shanks <bshanks@xxxxxxxxxxxxxxx>

Acked-by:  Jeremy White <jwhite@xxxxxxxxxxxxxxx>

> ---
> v2: Rename local variable 'fullscreen' to 'primary' in spice_start()
> ---
>   src/display.c     | 20 +++++++++++++++++++-
>   src/display.h     |  1 +
>   src/local_spice.h |  2 +-
>   src/main.c        |  2 +-
>   src/session.c     |  2 +-
>   src/spice.c       |  6 +++---
>   6 files changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/src/display.c b/src/display.c
> index 01e0e85..77b4d4e 100644
> --- a/src/display.c
> +++ b/src/display.c
> @@ -461,12 +461,25 @@ void destroy_shm_image(display_t *d, shm_image_t *shmi)
>   
>   int display_create_screen_images(display_t *d)
>   {
> +    /* 'primary' and 'fullscreen' don't need to be SHM, normal buffers would work
> +     * fine. Using SHM for all buffers is simpler though, and has no real downsides.
> +     */
> +    d->primary = create_shm_image(d, 0, 0);
> +    if (!d->primary) {
> +        return X11SPICE_ERR_NOSHM;
> +    }
> +
>       d->fullscreen = create_shm_image(d, 0, 0);
> -    if (!d->fullscreen)
> +    if (!d->fullscreen) {
> +        destroy_shm_image(d, d->primary);
> +        d->primary = NULL;
>           return X11SPICE_ERR_NOSHM;
> +    }
>   
>       d->scanline = create_shm_image(d, 0, 1);
>       if (!d->scanline) {
> +        destroy_shm_image(d, d->primary);
> +        d->primary = NULL;
>           destroy_shm_image(d, d->fullscreen);
>           d->fullscreen = NULL;
>           return X11SPICE_ERR_NOSHM;
> @@ -477,6 +490,11 @@ int display_create_screen_images(display_t *d)
>   
>   void display_destroy_screen_images(display_t *d)
>   {
> +    if (d->primary) {
> +        destroy_shm_image(d, d->primary);
> +        d->primary = NULL;
> +    }
> +
>       if (d->fullscreen) {
>           destroy_shm_image(d, d->fullscreen);
>           d->fullscreen = NULL;
> diff --git a/src/display.h b/src/display.h
> index dc4254b..27bc829 100644
> --- a/src/display.h
> +++ b/src/display.h
> @@ -55,6 +55,7 @@ typedef struct {
>   
>       const xcb_query_extension_reply_t *xfixes_ext;
>   
> +    shm_image_t *primary;
>       shm_image_t *fullscreen;
>       shm_image_t *scanline;
>   
> diff --git a/src/local_spice.h b/src/local_spice.h
> index 9d5e989..0573500 100644
> --- a/src/local_spice.h
> +++ b/src/local_spice.h
> @@ -61,7 +61,7 @@ typedef struct {
>   /*----------------------------------------------------------------------------
>   **  Prototypes
>   **--------------------------------------------------------------------------*/
> -int spice_start(spice_t *s, options_t *options, shm_image_t *fullscreen);
> +int spice_start(spice_t *s, options_t *options, shm_image_t *primary);
>   void spice_end(spice_t *s);
>   int spice_create_primary(spice_t *s, int w, int h, int bytes_per_line, void *shmaddr);
>   void spice_destroy_primary(spice_t *s);
> diff --git a/src/main.c b/src/main.c
> index cecadc8..71cbb46 100644
> --- a/src/main.c
> +++ b/src/main.c
> @@ -108,7 +108,7 @@ int main(int argc, char *argv[])
>       /*------------------------------------------------------------------------
>       **  Start up a spice server
>       **----------------------------------------------------------------------*/
> -    rc = spice_start(&session.spice, &session.options, session.display.fullscreen);
> +    rc = spice_start(&session.spice, &session.options, session.display.primary);
>       if (rc)
>           goto exit;
>       spice_started = 1;
> diff --git a/src/session.c b/src/session.c
> index 1e59415..4d72e14 100644
> --- a/src/session.c
> +++ b/src/session.c
> @@ -352,7 +352,7 @@ int session_recreate_primary(session_t *s)
>   
>       rc = display_create_screen_images(&s->display);
>       if (rc == 0) {
> -        shm_image_t *f = s->display.fullscreen;
> +        shm_image_t *f = s->display.primary;
>           rc = spice_create_primary(&s->spice, f->w, f->h, f->bytes_per_line, f->shmaddr);
>       }
>   
> diff --git a/src/spice.c b/src/spice.c
> index 430df40..cf7118f 100644
> --- a/src/spice.c
> +++ b/src/spice.c
> @@ -633,7 +633,7 @@ static int try_listen(spice_t *s, options_t *options)
>       return 0;
>   }
>   
> -int spice_start(spice_t *s, options_t *options, shm_image_t *fullscreen)
> +int spice_start(spice_t *s, options_t *options, shm_image_t *primary)
>   {
>       int rc;
>   
> @@ -678,8 +678,8 @@ int spice_start(spice_t *s, options_t *options, shm_image_t *fullscreen)
>   
>       spice_server_vm_start(s->server);
>   
> -    rc = spice_create_primary(s, fullscreen->w, fullscreen->h,
> -                              fullscreen->bytes_per_line, fullscreen->shmaddr);
> +    rc = spice_create_primary(s, primary->w, primary->h,
> +                              primary->bytes_per_line, primary->shmaddr);
>   
>       return rc;
>   }

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