[PATCH v4 1/2] lib/igt_device_scan: Extract helper setting device filter from fd

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]>
Reviewed-by: Marcin Bernatowicz <[email protected]>
---
 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);
 
-- 
2.43.0