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From: Marco Elver <elver@google.com>
To: elver@google.com
Cc: akiyks@gmail.com, stern@rowland.harvard.edu, glider@google.com,
	parri.andrea@gmail.com, andreyknvl@google.com, luto@kernel.org,
	ard.biesheuvel@linaro.org, arnd@arndb.de, boqun.feng@gmail.com,
	bp@alien8.de, dja@axtens.net, dlustig@nvidia.com,
	dave.hansen@linux.intel.com, dhowells@redhat.com,
	dvyukov@google.com, hpa@zytor.com, mingo@redhat.com,
	j.alglave@ucl.ac.uk, joel@joelfernandes.org, corbet@lwn.net,
	jpoimboe@redhat.com, luc.maranget@inria.fr, mark.rutland@arm.com,
	npiggin@gmail.com, paulmck@kernel.org, peterz@infradead.org,
	tglx@linutronix.de, will@kernel.org, edumazet@google.com,
	kasan-dev@googlegroups.com, linux-arch@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, x86@kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH v4 02/10] include/linux/compiler.h: Introduce data_race(expr) macro
Date: Thu, 14 Nov 2019 19:02:55 +0100
Message-ID: <20191114180303.66955-3-elver@google.com> (raw)
In-Reply-To: <20191114180303.66955-1-elver@google.com>

This introduces the data_race(expr) macro, which can be used to annotate
expressions for purposes of (1) documenting, and (2) giving tooling such
as KCSAN information about which data races are deemed "safe".

More context:
http://lkml.kernel.org/r/CAHk-=wg5CkOEF8DTez1Qu0XTEFw_oHhxN98bDnFqbY7HL5AB2g@mail.gmail.com

Signed-off-by: Marco Elver <elver@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
---
v4:
* Introduce this patch to KCSAN series.
---
 include/linux/compiler.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c42fa83f23fb..7d3e77781578 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -310,6 +310,26 @@ unsigned long read_word_at_a_time(const void *addr)
 	__u.__val;					\
 })
 
+#include <linux/kcsan.h>
+
+/*
+ * data_race: macro to document that accesses in an expression may conflict with
+ * other concurrent accesses resulting in data races, but the resulting
+ * behaviour is deemed safe regardless.
+ *
+ * This macro *does not* affect normal code generation, but is a hint to tooling
+ * that data races here should be ignored.
+ */
+#define data_race(expr)                                                        \
+	({                                                                     \
+		typeof(({ expr; })) __val;                                     \
+		kcsan_nestable_atomic_begin();                                 \
+		__val = ({ expr; });                                           \
+		kcsan_nestable_atomic_end();                                   \
+		__val;                                                         \
+	})
+#else
+
 #endif /* __KERNEL__ */
 
 /*
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog


  parent reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-14 18:02 [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN) Marco Elver
2019-11-14 18:02 ` [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure Marco Elver
2019-11-19 19:27   ` Qian Cai
2019-11-19 19:54     ` Marco Elver
2019-11-19 21:42       ` Qian Cai
2019-11-19 21:53         ` Marco Elver
2020-01-03  5:13   ` Qian Cai
2020-01-06 12:46     ` Marco Elver
2020-01-14 11:08       ` Qian Cai
2020-01-14 12:51         ` Marco Elver
2020-01-14 19:22         ` Paul E. McKenney
2020-01-14 20:30           ` Qian Cai
2020-01-14 21:34             ` Paul E. McKenney
2020-01-14 21:48               ` Qian Cai
2020-01-14 22:09                 ` Paul E. McKenney
2019-11-14 18:02 ` Marco Elver [this message]
2019-11-14 18:02 ` [PATCH v4 03/10] kcsan: Add Documentation entry in dev-tools Marco Elver
2019-11-14 18:02 ` [PATCH v4 04/10] objtool, kcsan: Add KCSAN runtime functions to whitelist Marco Elver
2019-11-14 18:02 ` [PATCH v4 05/10] build, kcsan: Add KCSAN build exceptions Marco Elver
2019-11-14 18:02 ` [PATCH v4 06/10] seqlock, kcsan: Add annotations for KCSAN Marco Elver
2019-11-14 18:03 ` [PATCH v4 07/10] seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier Marco Elver
2019-11-14 18:03 ` [PATCH v4 08/10] asm-generic, kcsan: Add KCSAN instrumentation for bitops Marco Elver
2019-11-15 11:55   ` Marco Elver
2019-11-14 18:03 ` [PATCH v4 09/10] locking/atomics, kcsan: Add KCSAN instrumentation Marco Elver
2019-11-14 18:03 ` [PATCH v4 10/10] x86, kcsan: Enable KCSAN for x86 Marco Elver
2019-11-14 19:50 ` [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN) Paul E. McKenney
2019-11-14 21:33   ` Marco Elver
2019-11-14 22:15     ` Paul E. McKenney
2019-11-15 12:02       ` Marco Elver
2019-11-15 16:41         ` Paul E. McKenney
2019-11-15 17:14           ` Marco Elver
2019-11-15 20:43             ` Paul E. McKenney
2019-11-16  8:20               ` Marco Elver
2019-11-16 15:34                 ` Paul E. McKenney
2019-11-16 18:09                   ` Marco Elver
2019-11-16 18:28                     ` Paul E. McKenney
2019-11-19 19:50 ` Qian Cai
2019-11-19 20:12 ` Qian Cai
2019-11-19 21:50   ` Marco Elver
2019-11-20 15:54     ` Marco Elver

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