Re: [PATCH 1/2] lib/igt_device_scan: Extract helper setting device filter from fd

On 7/29/2026 12:09 PM, Lukasz Laguna wrote:
> Helper sets device filter to the device corresponding to DRM device file
> descriptor. Move the implementation from core_hotunplug test into the
> library, so it can be reused in other tests.
>
> Signed-off-by: Lukasz Laguna <[email protected]>
> ---
> v3:
>   - move it to igt_device_scan (Janusz)
> ---
>   lib/igt_device_scan.c  | 23 +++++++++++++++++++++++
>   lib/igt_device_scan.h  |  2 ++
>   tests/core_hotunplug.c | 17 +----------------
>   3 files changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c
> index 7c7995224..decf19646 100644
> --- a/lib/igt_device_scan.c
> +++ b/lib/igt_device_scan.c
> @@ -2477,3 +2477,26 @@ int igt_device_prepare_filtered_view(const char *vendor)
>   
>   	return gpu_count;
>   }
> +
> +/**
> + * igt_device_set_filter_from_fd:
> + * @fd: DRM device file descriptor
> + *
> + * Set device filter to the device corresponding to @fd.
> + */
> +void igt_device_set_filter_from_fd(int fd)
> +{
> +	const char *filter_type = "sys:";
> +	char filter[strlen(filter_type) + PATH_MAX + 1];
> +	char *dst = stpcpy(filter, filter_type);
> +	char path[PATH_MAX + 1];
> +	struct stat st;
> +
> +	igt_assert(!fstat(fd, &st) && S_ISCHR(st.st_mode));
> +	snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device",
> +		 major(st.st_rdev), minor(st.st_rdev));
> +	igt_assert(realpath(path, dst));
> +
> +	igt_device_filter_free_all();
> +	igt_assert_eq(igt_device_filter_add(filter), 1);
> +}
> diff --git a/lib/igt_device_scan.h b/lib/igt_device_scan.h
> index f24a193cd..ac75fea8c 100644
> --- a/lib/igt_device_scan.h
> +++ b/lib/igt_device_scan.h
> @@ -103,4 +103,6 @@ int igt_open_render(struct igt_device_card *card);
>   /* Add or use filters to match multiGPU devices */
>   int igt_device_prepare_filtered_view(const char *vendor);
>   
> +void igt_device_set_filter_from_fd(int fd);
> +
>   #endif /* __IGT_DEVICE_SCAN_H__ */
> diff --git a/tests/core_hotunplug.c b/tests/core_hotunplug.c
> index 7c9dae1bf..33de65369 100644
> --- a/tests/core_hotunplug.c
> +++ b/tests/core_hotunplug.c
> @@ -550,21 +550,6 @@ static void post_healthcheck(struct hotunplug *priv)
>   	cleanup(priv);
>   }
>   
> -static void set_filter_from_device(int fd)
> -{
> -	const char *filter_type = "sys:";
> -	char filter[strlen(filter_type) + PATH_MAX + 1];
> -	char *dst = stpcpy(filter, filter_type);
> -	char path[PATH_MAX + 1];
> -
> -	igt_assert(igt_sysfs_path(fd, path, PATH_MAX));
> -	igt_ignore_warn(strncat(path, "/device", PATH_MAX - strlen(path)));
> -	igt_assert(realpath(path, dst));
> -
> -	igt_device_filter_free_all();
> -	igt_assert_eq(igt_device_filter_add(filter), 1);
> -}
> -
>   /* Subtests */
>   
>   static void unbind_rebind(struct hotunplug *priv)
> @@ -713,7 +698,7 @@ int igt_main()
>   		}
>   
>   		/* Make sure subtests always reopen the same device */
> -		set_filter_from_device(fd_drm);
> +		igt_device_set_filter_from_fd(fd_drm);
>   
>   		igt_assert_eq(close_device(fd_drm, "", "selected "), -1);
>   

LGTM,

Reviewed-by: Marcin Bernatowicz <[email protected]>