[tip: locking/core] compiler-context-analysis: Add test stub

["tip-bot2 for Marco Elver" <tip-bot2@linutronix.de>]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     9b00c1609deeb7d6f68a61f3ec6988ab7e6f4535
Gitweb:        https://git.kernel.org/tip/9b00c1609deeb7d6f68a61f3ec6988ab7e6f4535
Author:        Marco Elver <elver@google.com>
AuthorDate:    Fri, 19 Dec 2025 16:39:52 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 05 Jan 2026 16:43:27 +01:00

compiler-context-analysis: Add test stub

Add a simple test stub where we will add common supported patterns that
should not generate false positives for each new supported context lock.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-4-elver@google.com
---
 lib/Kconfig.debug           | 14 ++++++++++++++
 lib/Makefile                |  3 +++
 lib/test_context-analysis.c | 18 ++++++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 lib/test_context-analysis.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cd557e7..8ca4252 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2835,6 +2835,20 @@ config LINEAR_RANGES_TEST
 
 	  If unsure, say N.
 
+config CONTEXT_ANALYSIS_TEST
+	bool "Compiler context-analysis warnings test"
+	depends on EXPERT
+	help
+	  This builds the test for compiler-based context analysis. The test
+	  does not add executable code to the kernel, but is meant to test that
+	  common patterns supported by the analysis do not result in false
+	  positive warnings.
+
+	  When adding support for new context locks, it is strongly recommended
+	  to add supported patterns to this test.
+
+	  If unsure, say N.
+
 config CMDLINE_KUNIT_TEST
 	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index aaf677c..89defef 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -331,4 +331,7 @@ obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 
 obj-$(CONFIG_FIRMWARE_TABLE) += fw_table.o
 
+CONTEXT_ANALYSIS_test_context-analysis.o := y
+obj-$(CONFIG_CONTEXT_ANALYSIS_TEST) += test_context-analysis.o
+
 subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify
diff --git a/lib/test_context-analysis.c b/lib/test_context-analysis.c
new file mode 100644
index 0000000..68f075d
--- /dev/null
+++ b/lib/test_context-analysis.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Compile-only tests for common patterns that should not generate false
+ * positive errors when compiled with Clang's context analysis.
+ */
+
+#include <linux/build_bug.h>
+
+/*
+ * Test that helper macros work as expected.
+ */
+static void __used test_common_helpers(void)
+{
+	BUILD_BUG_ON(context_unsafe(3) != 3); /* plain expression */
+	BUILD_BUG_ON(context_unsafe((void)2; 3) != 3); /* does not swallow semi-colon */
+	BUILD_BUG_ON(context_unsafe((void)2, 3) != 3); /* does not swallow commas */
+	context_unsafe(do { } while (0)); /* works with void statements */
+}