[igt-dev] [RFC PATCH i-g-t 1/2] lib/core: Add igt_debug_on* variants

[Janusz Krzysztofik]

If a test calls a function which can return a failure, only the fact
that the function failed can be reported to the caller, with no details
on what actually failed inside.  It could be helpful if functions which
perform several steps or iterations emitted debug messages with failure
details.

To simplify coding and avoid code duplication in functions, igt_debug
variants similar to igt_warn_on and friends could be useful.  Add them.

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
---
 lib/igt_core.h | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/lib/igt_core.h b/lib/igt_core.h
index 6075d1539..8d433fc16 100644
--- a/lib/igt_core.h
+++ b/lib/igt_core.h
@@ -1274,6 +1274,58 @@ extern enum igt_log_level igt_log_level;
 		ret__; \
 	})
 
+/**
+ * igt_debug_on:
+ * @condition: condition to test
+ *
+ * Print a IGT_LOG_DEBUG level message if a condition is met.
+ *
+ * Should be used when something fails in a function that doesn't perform
+ * a long jump in that case, and either performs several operations that
+ * can fail that way or doesn't return unambiguous error codes on failures.
+ * This is useful to streamline the test logic since it allows for
+ * replacing open conding with function calls without loosing ability to
+ * provide debug output with failure details.
+ *
+ * This macro also returns the value of @condition.
+ */
+#define igt_debug_on(condition) ({ \
+		typeof(condition) ret__ = (condition); \
+		if (ret__) \
+			igt_debug("Condition %s occurred in function %s, file %s:%i\n", \
+				  #condition, __func__, __FILE__, __LINE__); \
+		ret__; \
+	})
+
+/**
+ * igt_debug_on_f:
+ * @condition: condition to test
+ * @...: format string and optional arguments
+ *
+ * Print a IGT_LOG_DEBUG level message if a condition is met.
+ *
+ * Should be used when something fails in a function that doesn't perform
+ * a long jump in that case, and performs one or more operations in a
+ * loop, each time with different values of parameters.  This is useful
+ * to streamline the test logic since it allows for replacing open conding
+ * with function calls without loosing ability to provide debug output
+ * with failure details.
+ *
+ * In addition to the plain igt_debug_on() helper this allows to print
+ * additional debug information to help debugging operation failures.
+ *
+ * It also returns the value of @condition.
+ */
+#define igt_debug_on_f(condition, f...) ({ \
+		typeof(condition) ret__ = (condition); \
+		if (ret__) {\
+			igt_debug("condition %s occurred in function %s, file %s:%i\n", \
+				  #condition, __func__, __FILE__, __LINE__); \
+			igt_debug(f); \
+		} \
+		ret__; \
+	})
+
 void igt_set_timeout(unsigned int seconds,
 		     const char *op);
 
-- 
2.25.1