tests: introduce igt_require

Since igt_skip has funny control flow we can abuse it and make it work
like a special kind of assert which automatically skips tests if a
requirement fails.

Note that in places where we have a less strict test which should
always succeed (e.g. ioctl works or isn't available) the igt_assert
should be place before the igt_require with the more strict
requirements. Otherwise we'll skip a test instead of properly failing
it.

Convert a few users of igt_skip over to igt_require to showcase its
use.

v2: s/gem_check_/gem_require_/ so that we consistently use "require"
to indicate magic check that can call igt_skip. Imo hiding the
igt_require for feature checks is ok, but for more traditional assert
like use cases an explicit igt_require might be better.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/drmtest.c

@@ -393,7 +393,7 @@ struct local_drm_i915_gem_caching {
 #define LOCAL_DRM_IOCTL_I915_GEM_GET_CACHEING \
 	DRM_IOWR(DRM_COMMAND_BASE + LOCAL_DRM_I915_GEM_GET_CACHEING, struct local_drm_i915_gem_caching)
 
-void gem_check_caching(int fd)
+void gem_require_caching(int fd)
 {
 	struct local_drm_i915_gem_caching arg;
 	int ret;
@@ -405,11 +405,7 @@ void gem_check_caching(int fd)
 	ret = ioctl(fd, LOCAL_DRM_IOCTL_I915_GEM_SET_CACHEING, &arg);
 	gem_close(fd, arg.handle);
 
-	if (ret != 0) {
-		if (!igt_only_list_subtests())
-			printf("no set_caching support detected\n");
-		igt_skip();
-	}
+	igt_require(ret == 0);
 }
 
 void gem_set_caching(int fd, uint32_t handle, int caching)
@@ -421,10 +417,8 @@ void gem_set_caching(int fd, uint32_t handle, int caching)
 	arg.caching = caching;
 	ret = ioctl(fd, LOCAL_DRM_IOCTL_I915_GEM_SET_CACHEING, &arg);
 
-	if (ret != 0 && (errno == ENOTTY || errno == EINVAL))
-		igt_skip();
-	else
-		igt_assert(ret == 0);
+	igt_assert(ret == 0 || (errno == ENOTTY || errno == EINVAL));
+	igt_require(ret == 0);
 }
 
 uint32_t gem_get_caching(int fd, uint32_t handle)
@@ -770,6 +764,15 @@ void igt_skip(void)
 		exit(77);
 }
 
+void __igt_skip_check(const char *file, const int line,
+		      const char *func, const char *check)
+{
+	printf("Test requirement not met in function %s, file %s:%i:\n"
+	       "Test requirement: (%s)\n",
+	       func, file, line, check);
+	igt_skip();
+}
+
 void igt_success(void)
 {
 	succeeded_one = true;
@@ -847,8 +850,7 @@ void igt_skip_on_simulation(void)
 	if (igt_only_list_subtests())
 		return;
 
-	if (igt_run_in_simulation())
-		igt_skip();
+	igt_require(!igt_run_in_simulation());
 }
 
 /* other helpers */

lib/drmtest.h

@@ -36,6 +36,7 @@
 
 #include "xf86drm.h"
 #include "xf86drmMode.h"
+#include "i915_drm.h"
 #include "intel_batchbuffer.h"
 #include "intel_chipset.h"
 #include "intel_gpu_tools.h"
@@ -104,41 +105,48 @@ bool __igt_run_subtest(const char *subtest_name);
 				   igt_success())
 bool igt_only_list_subtests(void);
 void igt_skip(void);
+void __igt_skip_check(const char *file, const int line,
+		      const char *func, const char *check);
 void igt_success(void);
 void igt_fail(int exitcode) __attribute__((noreturn));
 void __igt_fail_assert(int exitcode, const char *file,
 		       const int line, const char *func, const char *assertion)
 	__attribute__((noreturn));
 void igt_exit(void);
+/**
+ * igt_assert - fails (sub-)test if a condition is not met
+ *
+ * Should be used everywhere where a test checks results.
+ */
 #define igt_assert(expr) do { if (!(expr)) __igt_fail_assert(99, __FILE__, __LINE__, __func__, #expr ); } while (0)
+/**
+ * igt_require - skip a (sub-)test if a condition is not met
+ *
+ * This is useful to streamline the skip logic since it allows for a more flat
+ * code control flow.
+ */
+#define igt_require(expr) do { if (!(expr)) __igt_skip_check(__FILE__, __LINE__, __func__, #expr ); } while (0)
 
 /* check functions which auto-skip tests by calling igt_skip() */
-void gem_check_caching(int fd);
-static inline bool gem_check_vebox(int fd)
+void gem_require_caching(int fd);
+static inline void gem_require_ring(int fd, int ring_id)
 {
-	if (gem_has_vebox(fd))
-		return true;
-
-	igt_skip();
-	return false;
-}
-
-static inline bool gem_check_bsd(int fd)
-{
-	if (HAS_BSD_RING(intel_get_drm_devid(fd)))
-		return true;
-
-	igt_skip();
-	return false;
-}
-
-static inline bool gem_check_blt(int fd)
-{
-	if (HAS_BLT_RING(intel_get_drm_devid(fd)))
-		return true;
-
-	igt_skip();
-	return false;
+	switch (ring_id) {
+	case I915_EXEC_RENDER:
+		return;
+	case I915_EXEC_BLT:
+		igt_require(HAS_BLT_RING(intel_get_drm_devid(fd)));
+		return;
+	case I915_EXEC_BSD:
+		igt_require(HAS_BSD_RING(intel_get_drm_devid(fd)));
+		return;
+	case I915_EXEC_VEBOX:
+		igt_require(gem_has_vebox(fd));
+		return;
+	default:
+		assert(0);
+		return;
+	}
 }
 
 /* helpers to automatically reduce test runtime in simulation */