[PATCH xwayland] xwayland: Don't load extension list more then once

[Michel Dänzer]

On 31/05/17 05:39 AM, Lyude wrote:
> When running an Xwayland server from the command line, we end up
> resetting the server every time all of the clients connected to the
> server leave. This would be fine, except that xwayland makes the mistake
> of unconditionally calling LoadExtensionList(). This causes us to setup
> the glxExtension twice in a row which means that when we lose our last
> client on the second server generation, we end up trying to call the glx
> destructors twice in a row resulting in a segfault:
> 
> (EE)
> (EE) Backtrace:
> (EE) 0: Xwayland (OsSigHandler+0x3b) [0x4982f9]
> (EE) 1: /lib64/libpthread.so.0 (__restore_rt+0x0) [0x70845bf]
> (EE) 2: /usr/lib64/dri/swrast_dri.so (__driDriverGetExtensions_virtio_gpu+0x32897d) [0x1196e5bd]
> (EE) 3: /usr/lib64/dri/swrast_dri.so (__driDriverGetExtensions_virtio_gpu+0x328a45) [0x1196e745]
> (EE) 4: /usr/lib64/dri/swrast_dri.so (__driDriverGetExtensions_virtio_gpu+0x32665f) [0x11969f7f]
> (EE) 5: Xwayland (__glXDRIscreenDestroy+0x30) [0x54686e]
> (EE) 6: Xwayland (glxCloseScreen+0x3f) [0x5473db]
> (EE) 7: Xwayland (glxCloseScreen+0x53) [0x5473ef]
> (EE) 8: Xwayland (dix_main+0x7b6) [0x44c8c9]
> (EE) 9: Xwayland (main+0x28) [0x61c503]
> (EE) 10: /lib64/libc.so.6 (__libc_start_main+0xf1) [0x72b1401]
> (EE) 11: Xwayland (_start+0x2a) [0x4208fa]
> (EE) 12: ? (?+0x2a) [0x2a]
> (EE)
> (EE) Segmentation fault at address 0x18
> (EE)
> Fatal server error:
> (EE) Caught signal 11 (Segmentation fault). Server aborting
> (EE)
> 
> Easy reproduction recipe:
> - Start an Xwayland session with the default settings
> - Open a window
> - Close that window
> - Open another window
> - Close that window
> - Total annihilation occurs
> 
> Signed-off-by: Lyude <lyude at redhat.com>
> ---
>  hw/xwayland/xwayland.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c
> index 7fc9bc0..cc638ff 100644
> --- a/hw/xwayland/xwayland.c
> +++ b/hw/xwayland/xwayland.c
> @@ -1013,8 +1013,9 @@ InitOutput(ScreenInfo * screen_info, int argc, char **argv)
>      screen_info->bitmapBitOrder = BITMAP_BIT_ORDER;
>      screen_info->numPixmapFormats = ARRAY_SIZE(depths);
>  
> -    LoadExtensionList(xwayland_extensions,
> -                      ARRAY_SIZE(xwayland_extensions), FALSE);
> +    if (serverGeneration == 1)
> +        LoadExtensionList(xwayland_extensions,
> +                          ARRAY_SIZE(xwayland_extensions), FALSE);
>  
>      /* Cast away warning from missing printf annotation for
>       * wl_log_func_t.  Wayland 1.5 will have the annotation, so we can
> 

Good catch.

Reviewed-by: Michel Dänzer <michel.daenzer at amd.com>


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer