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From: Marco Elver <elver@google.com>
To: elver@google.com
Cc: paulmck@kernel.org, andreyknvl@google.com, glider@google.com,
	dvyukov@google.com, kasan-dev@googlegroups.com,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] kcsan: Clarify Kconfig option KCSAN_IGNORE_ATOMICS
Date: Tue,  4 Feb 2020 15:03:52 +0100	[thread overview]
Message-ID: <20200204140353.177797-2-elver@google.com> (raw)
In-Reply-To: <20200204140353.177797-1-elver@google.com>

Clarify difference between options KCSAN_IGNORE_ATOMICS and
KCSAN_ASSUME_PLAIN_WRITES_ATOMIC in help text.

Signed-off-by: Marco Elver <elver@google.com>
---
 lib/Kconfig.kcsan | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 08972376f0454..35fab63111d75 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -131,8 +131,17 @@ config KCSAN_ASSUME_PLAIN_WRITES_ATOMIC
 config KCSAN_IGNORE_ATOMICS
 	bool "Do not instrument marked atomic accesses"
 	help
-	  If enabled, never instruments marked atomic accesses. This results in
-	  not reporting data races where one access is atomic and the other is
-	  a plain access.
+	  Never instrument marked atomic accesses. This option can be used for
+	  more advanced filtering. Conflicting marked atomic reads and plain
+	  writes will never be reported as a data race, however, will cause
+	  plain reads and marked writes to result in "unknown origin" reports.
+	  If combined with CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN=n, data
+	  races where at least one access is marked atomic will never be
+	  reported.
+
+	  Like KCSAN_ASSUME_PLAIN_WRITES_ATOMIC, conflicting marked atomic
+	  reads and plain writes will not be reported as data races, however,
+	  unlike that option, data races due to two conflicting plain writes
+	  will be reported (if CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n).
 
 endif # KCSAN
-- 
2.25.0.341.g760bfbb309-goog


  reply	other threads:[~2020-02-04 14:04 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 14:03 [PATCH 1/3] kcsan: Add option to assume plain writes up to word size are atomic Marco Elver
2020-02-04 14:03 ` Marco Elver [this message]
2020-02-04 14:03 ` [PATCH 3/3] kcsan: Cleanup of main KCSAN Kconfig option Marco Elver
2020-02-04 15:28 ` [PATCH 1/3] kcsan: Add option to assume plain writes up to word size are atomic Marco Elver
2020-02-04 15:40   ` Paul E. McKenney
2020-02-04 17:22     ` Marco Elver

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