[PATCH 21/59] drm/amd/display: Model ASSERT as path terminator

[WHAT]
ASSERT() and ASSERT_CRITICAL() expand to a WARN_ON() test that falls
through, because dc_breakpoint() is a no-op unless
CONFIG_DEBUG_KERNEL_DC is set.

Static analysers read that test as proof the asserted condition can
fail, then keep walking the failing path because nothing stops it. The
assert therefore manufactures the very defect it guards against, and
Coverity reports DIVIDE_BY_ZERO defects whose entire path is the assert
itself.

[HOW]
Redefine both macros to call a declaration-only __coverity_panic__()
when the asserted condition fails, which marks the failing path as
unreachable and leaves only genuinely reachable defects.

The override is guarded by __COVERITY__, which is defined only while
the analyser captures the build, so the code emitted by a normal build
is unchanged.

Assisted-by: Copilot:Claude-Opus-5
Reviewed-by: Harry Wentland <[email protected]>
Signed-off-by: Alex Hung <[email protected]>
---
 drivers/gpu/drm/amd/display/dc/os_types.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/os_types.h b/drivers/gpu/drm/amd/display/dc/os_types.h
index 538d00105738..339372293a98 100644
--- a/drivers/gpu/drm/amd/display/dc/os_types.h
+++ b/drivers/gpu/drm/amd/display/dc/os_types.h
@@ -78,6 +78,23 @@
 #define dc_breakpoint()		do {} while (0)
 #endif
 
+#ifdef __COVERITY__
+/*
+ * Static analysers see the WARN_ON() test as proof that the asserted condition
+ * can fail, then keep walking the failing path because nothing stops it. Model
+ * the assert as a path terminator so only genuinely reachable defects survive.
+ * __COVERITY__ is defined during analysis capture only, so the code emitted by
+ * a real build is unchanged.
+ */
+void __coverity_panic__(void);
+
+#define ASSERT_CRITICAL(expr) do {		\
+		if (!(expr))			\
+			__coverity_panic__();	\
+	} while (0)
+
+#define ASSERT(expr) ASSERT_CRITICAL(expr)
+#else
 #define ASSERT_CRITICAL(expr) do {		\
 		if (WARN_ON(!(expr)))		\
 			dc_breakpoint();	\
@@ -87,6 +104,7 @@
 		if (WARN_ON_ONCE(!(expr)))	\
 			dc_breakpoint();	\
 	} while (0)
+#endif
 
 #define BREAK_TO_DEBUGGER() \
 	do { \
-- 
2.43.0