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Date:   Mon,  7 Jun 2021 14:56:52 +0200
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Subject: [PATCH 6/7] kcsan: Print if strict or non-strict during init
From:   Marco Elver <elver@google.com>
To:     elver@google.com, paulmck@kernel.org
Cc:     boqun.feng@gmail.com, mark.rutland@arm.com, will@kernel.org,
        glider@google.com, dvyukov@google.com, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org
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Show a brief message if KCSAN is strict or non-strict, and if non-strict
also say that CONFIG_KCSAN_STRICT=y can be used to see all data races.

This is to hint to users of KCSAN who blindly use the default config
that their configuration might miss data races of interest.

Signed-off-by: Marco Elver <elver@google.com>
---
 kernel/kcsan/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 439edb9dcbb1..76e67d1e02d4 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -656,6 +656,15 @@ void __init kcsan_init(void)
 		pr_info("enabled early\n");
 		WRITE_ONCE(kcsan_enabled, true);
 	}
+
+	if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) ||
+	    IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC) ||
+	    IS_ENABLED(CONFIG_KCSAN_PERMISSIVE) ||
+	    IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
+		pr_warn("non-strict mode configured - use CONFIG_KCSAN_STRICT=y to see all data races\n");
+	} else {
+		pr_info("strict mode configured\n");
+	}
 }
 
 /* === Exported interface =================================================== */
-- 
2.32.0.rc1.229.g3e70b5a671-goog