Commit 3635ad87 authored by Marco Elver's avatar Marco Elver Committed by Peter Zijlstra
Browse files

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: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-27-elver@google.com
parent c237f1ce

include/linux/compiler.h

+2 −0
Original line number Diff line number Diff line
@@ -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;								\

})

lib/test_context-analysis.c

+2 −0
Original line number Diff line number Diff line
@@ -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);