[PATCH v2 3/7] drm/xe/rtp: Don't short-circuit to false in or-yes case

[Gustavo Sousa <gustavo.sousa@intel.com>]

While RTP processing evaluates true on the "yes-or" case (i.e. a
conjunction of rules that evaluate to true followed by an "OR" without
the right hand operand), it does not on the "or-yes" one.

Both cases are considered malformed and could be a result of someone
dropping checks deemed not necessary anymore and forgetting to drop the
superfluous "OR".  Nevertheless, we should aim for consistency, and
having the "or-yes" case also evaluating to true while also causing a
warning seems reasonable.  So let's do that.

The "or-yes" pattern being evaluated to false comes from the fact that
that we unconditionally short-circuit upon finding XE_RTP_MATCH_OR on
the outer loop.  We should only do that if the preceding conjunction of
rules evaluated to true (meaning that rcount must be non-zero) and
continue the evaluation otherwise.

Do that and also add extra test cases to validate the short-circuiting
behavior.

Notice that some of the new test cases have a "FIXME" comment, which
comes from the fact that we are unable to detect syntax errors after the
short-circuit point.  That is going to be fixed in a follow-up change.

Link: https://lore.kernel.org/intel-xe/871pfw4lo9.fsf@intel.com/
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
---
 drivers/gpu/drm/xe/tests/xe_rtp_test.c | 42 ++++++++++++++++++++++++++++++++--
 drivers/gpu/drm/xe/xe_rtp.c            | 15 ++++++++----
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/xe/tests/xe_rtp_test.c b/drivers/gpu/drm/xe/tests/xe_rtp_test.c
index 7dce699991a1..5e0afde9eab4 100644
--- a/drivers/gpu/drm/xe/tests/xe_rtp_test.c
+++ b/drivers/gpu/drm/xe/tests/xe_rtp_test.c
@@ -172,11 +172,49 @@ static const struct rtp_rules_test_case rtp_rules_cases[] = {
 		XE_RTP_RULES(OR),
 	},
 	{
-		.name = "or-anything",
-		.expected_match = false,
+		.name = "or-yes",
+		.expected_match = true,
 		.expected_err = -EINVAL,
 		XE_RTP_RULES(OR, FUNC(match_yes)),
 	},
+	{
+		.name = "or-no",
+		.expected_match = false,
+		.expected_err = -EINVAL,
+		XE_RTP_RULES(OR, FUNC(match_no)),
+	},
+	{
+		.name = "yes-or",
+		.expected_match = true,
+		/* FIXME: The parser should raise an error here. */
+		.expected_err = 0,
+		XE_RTP_RULES(FUNC(match_yes), OR),
+	},
+	{
+		.name = "no-or",
+		.expected_match = false,
+		.expected_err = -EINVAL,
+		XE_RTP_RULES(FUNC(match_no), OR),
+	},
+	{
+		.name = "no-or-or-yes",
+		.expected_match = true,
+		.expected_err = -EINVAL,
+		XE_RTP_RULES(FUNC(match_no), OR, OR, FUNC(match_yes)),
+	},
+	{
+		.name = "yes-or-or-no",
+		.expected_match = true,
+		/* FIXME: The parser should raise an error here. */
+		.expected_err = 0,
+		XE_RTP_RULES(FUNC(match_yes), OR, OR, FUNC(match_no)),
+	},
+	{
+		.name = "no-or-or-no",
+		.expected_match = false,
+		.expected_err = -EINVAL,
+		XE_RTP_RULES(FUNC(match_no), OR, OR, FUNC(match_no)),
+	},
 };
 
 static void xe_rtp_rules_tests(struct kunit *test)
diff --git a/drivers/gpu/drm/xe/xe_rtp.c b/drivers/gpu/drm/xe/xe_rtp.c
index 0e1adf07e4e7..299fa4209a26 100644
--- a/drivers/gpu/drm/xe/xe_rtp.c
+++ b/drivers/gpu/drm/xe/xe_rtp.c
@@ -47,12 +47,18 @@ static bool rule_matches_with_err(const struct xe_device *xe,
 	for (r = rules, i = 0; i < n_rules; r = &rules[++i]) {
 		switch (r->match_type) {
 		case XE_RTP_MATCH_OR:
+			if (drm_WARN_ON(&xe->drm, !rcount)) {
+				if (err)
+					*err = -EINVAL;
+				continue;
+			}
+
 			/*
-			 * This is only reached if a complete set of
-			 * rules passed or none were evaluated. For both cases,
-			 * shortcut the other rules and return the proper value.
+			 * This is only reached if a complete conjunction of
+			 * rules passed, in which case we shortcut the other
+			 * rules and return true.
 			 */
-			goto done;
+			return true;
 		case XE_RTP_MATCH_PLATFORM:
 			match = xe->info.platform == r->platform;
 			break;
@@ -169,7 +175,6 @@ static bool rule_matches_with_err(const struct xe_device *xe,
 		}
 	}
 
-done:
 	if (drm_WARN_ON(&xe->drm, !rcount))
 		goto error;
 

-- 
2.53.0