This will not work as-is for radv, as failure to initialize from
wsi_display_init_wsi (->wsi_device_init -> radv_init_wsi) will cause
us to fail initializing the whole device.
On Wed, Apr 17, 2019 at 7:02 PM Emil Velikov <emil.l.veli...@gmail.com> wrote:
>
> From: Emil Velikov <emil.veli...@collabora.com>
>
> As effectively required by the extension, we need to ensure we're master
>
> Currently drivers employ vendor specific solutions, which check if the
> device behind the fd is capable*, yet none of them do the master check.
>
> *In the radv case, if acceleration is available.
>
> Instead of duplicating the check in each driver, keep it where it's
> needed and used.
>
> Note this copies libdrm's drmIsMaster() to avoid depending on bleeding
> edge version of the library.
>
> Cc: Keith Packard <kei...@keithp.com>
> Cc: Jason Ekstrand <ja...@jlekstrand.net>
> Cc: Bas Nieuwenhuizen <b...@basnieuwenhuizen.nl>
> Cc: Andres Rodriguez <andre...@gmail.com>
> Reported-by: Andres Rodriguez <andre...@gmail.com>
> Fixes: da997ebec92 ("vulkan: Add KHR_display extension using DRM [v10]")
> Signed-off-by: Emil Velikov <emil.veli...@collabora.com>
> ---
> src/vulkan/wsi/wsi_common_display.c | 30 +++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/src/vulkan/wsi/wsi_common_display.c
> b/src/vulkan/wsi/wsi_common_display.c
> index 74ed36ed646..d6b2ae004ce 100644
> --- a/src/vulkan/wsi/wsi_common_display.c
> +++ b/src/vulkan/wsi/wsi_common_display.c
> @@ -1812,6 +1812,30 @@ fail_attr_init:
> return ret;
> }
>
> +
> +/*
> + * Local version fo the libdrm helper. Added to avoid depending on bleeding
> + * edge version of the library.
> + */
> +static int
> +local_drmIsMaster(int fd)
> +{
> + /* Detect master by attempting something that requires master.
> + *
> + * Authenticating magic tokens requires master and 0 is an
> + * internal kernel detail which we could use. Attempting this on
> + * a master fd would fail therefore fail with EINVAL because 0
> + * is invalid.
> + *
> + * A non-master fd will fail with EACCES, as the kernel checks
> + * for master before attempting to do anything else.
> + *
> + * Since we don't want to leak implementation details, use
> + * EACCES.
> + */
> + return drmAuthMagic(fd, 0) != -EACCES;
> +}
> +
> VkResult
> wsi_display_init_wsi(struct wsi_device *wsi_device,
> const VkAllocationCallbacks *alloc,
> @@ -1826,6 +1850,11 @@ wsi_display_init_wsi(struct wsi_device *wsi_device,
> goto fail;
> }
>
> + if (!local_drmIsMaster(display_fd)) {
> + result = VK_ERROR_INITIALIZATION_FAILED;
> + goto fail_fd;
> + }
> +
> wsi->fd = display_fd;
> wsi->alloc = alloc;
>
> @@ -1857,6 +1886,7 @@ wsi_display_init_wsi(struct wsi_device *wsi_device,
> fail_cond:
> pthread_mutex_destroy(&wsi->wait_mutex);
> fail_mutex:
> +fail_fd:
> vk_free(alloc, wsi);
> fail:
> return result;
> --
> 2.21.0
>
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