linux-kernel - [tip: locking/core] compiler: Let data_race() imply disabled context analysis

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Message-ID: <176762846088.510.2120927185812788776.tip-bot2@tip-bot2>
Date: Mon, 05 Jan 2026 15:54:20 -0000
From: "tip-bot2 for Marco Elver" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Marco Elver <elver@...gle.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: locking/core] compiler: Let data_race() imply disabled context analysis

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

Commit-ID:     3635ad878242487fc3e8165d0329aedb118e4608
Gitweb:        https://git.kernel.org/tip/3635ad878242487fc3e8165d0329aedb118e4608
Author:        Marco Elver <elver@...gle.com>
AuthorDate:    Fri, 19 Dec 2025 16:40:15 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 05 Jan 2026 16:43:34 +01:00

compiler: Let data_race() imply disabled context analysis

Many patterns that involve data-racy accesses often deliberately ignore
normal synchronization rules to avoid taking a lock.

If we have a lock-guarded variable on which we do a lock-less data-racy
access, rather than having to write context_unsafe(data_race(..)),
simply make the data_race(..) macro imply context-unsafety. The
data_race() macro already denotes the intent that something subtly
unsafe is about to happen, so it should be clear enough as-is.

Signed-off-by: Marco Elver <elver@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://patch.msgid.link/20251219154418.3592607-27-elver@google.com
---
 include/linux/compiler.h    | 2 ++
 lib/test_context-analysis.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 04487c9..110b28d 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -190,7 +190,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define data_race(expr)							\
 ({									\
 	__kcsan_disable_current();					\
+	disable_context_analysis();					\
 	auto __v = (expr);						\
+	enable_context_analysis();					\
 	__kcsan_enable_current();					\
 	__v;								\
 })
diff --git a/lib/test_context-analysis.c b/lib/test_context-analysis.c
index 2dc4044..1c5a381 100644
--- a/lib/test_context-analysis.c
+++ b/lib/test_context-analysis.c
@@ -92,6 +92,8 @@ static void __used test_raw_spinlock_trylock_extra(struct test_raw_spinlock_data
 {
 	unsigned long flags;
 
+	data_race(d->counter++); /* no warning */
+
 	if (raw_spin_trylock_irq(&d->lock)) {
 		d->counter++;
 		raw_spin_unlock_irq(&d->lock);