kcsan: Improve some Kconfig comments

Improve comment for CC_HAS_TSAN_COMPOUND_READ_BEFORE_WRITE. Also shorten
the comment above the "strictness" configuration options.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 0440f37..6152fbd 100644 (file)
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -40,10 +40,14 @@ menuconfig KCSAN
 
 if KCSAN
 
-# Compiler capabilities that should not fail the test if they are unavailable.
 config CC_HAS_TSAN_COMPOUND_READ_BEFORE_WRITE
        def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-compound-read-before-write=1)) || \
                 (CC_IS_GCC && $(cc-option,-fsanitize=thread --param tsan-compound-read-before-write=1))
+       help
+         The compiler instruments plain compound read-write operations
+         differently (++, --, +=, -=, |=, &=, etc.), which allows KCSAN to
+         distinguish them from other plain accesses. This is currently
+         supported by Clang 12 or later.
 
 config KCSAN_VERBOSE
        bool "Show verbose reports with more information about system state"
@@ -169,13 +173,9 @@ config KCSAN_REPORT_ONCE_IN_MS
          reporting to avoid flooding the console with reports.  Setting this
          to 0 disables rate limiting.
 
-# The main purpose of the below options is to control reported data races (e.g.
-# in fuzzer configs), and are not expected to be switched frequently by other
-# users. We could turn some of them into boot parameters, but given they should
-# not be switched normally, let's keep them here to simplify configuration.
-#
-# The defaults below are chosen to be very conservative, and may miss certain
-# bugs.
+# The main purpose of the below options is to control reported data races, and
+# are not expected to be switched frequently by non-testers or at runtime.
+# The defaults are chosen to be conservative, and can miss certain bugs.
 
 config KCSAN_REPORT_RACE_UNKNOWN_ORIGIN
        bool "Report races of unknown origin"