From 247dbcdbf790c52fc76cf8e327cd0a5778e41e66 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Wed, 4 Oct 2023 17:53:07 +0100 Subject: bitops: add xor_unlock_is_negative_byte() Replace clear_bit_and_unlock_is_negative_byte() with xor_unlock_is_negative_byte(). We have a few places that like to lock a folio, set a flag and unlock it again. Allow for the possibility of combining the latter two operations for efficiency. We are guaranteed that the caller holds the lock, so it is safe to unlock it with the xor. The caller must guarantee that nobody else will set the flag without holding the lock; it is not safe to do this with the PG_dirty flag, for example. Link: https://lkml.kernel.org/r/20231004165317.1061855-8-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Geert Uytterhoeven Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton --- kernel/kcsan/kcsan_test.c | 8 ++++---- kernel/kcsan/selftest.c | 8 ++++---- 2 files changed, 8 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c index 0ddbdab5903d..1333d23ac4ef 100644 --- a/kernel/kcsan/kcsan_test.c +++ b/kernel/kcsan/kcsan_test.c @@ -700,10 +700,10 @@ static void test_barrier_nothreads(struct kunit *test) KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false); KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true); -#ifdef clear_bit_unlock_is_negative_byte - KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true); - KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true); - KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true); +#ifdef xor_unlock_is_negative_byte + KCSAN_EXPECT_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true); + KCSAN_EXPECT_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true); + KCSAN_EXPECT_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true); #endif kcsan_nestable_atomic_end(); } diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c index 8679322450f2..619be7417420 100644 --- a/kernel/kcsan/selftest.c +++ b/kernel/kcsan/selftest.c @@ -228,10 +228,10 @@ static bool __init test_barrier(void) spin_lock(&test_spinlock); KCSAN_CHECK_RW_BARRIER(spin_unlock(&test_spinlock)); -#ifdef clear_bit_unlock_is_negative_byte - KCSAN_CHECK_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var)); - KCSAN_CHECK_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var)); - KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var)); +#ifdef xor_unlock_is_negative_byte + KCSAN_CHECK_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); + KCSAN_CHECK_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); + KCSAN_CHECK_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var)); #endif kcsan_nestable_atomic_end(); -- cgit v1.2.3