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[188.147.112.12]) by smtp.gmail.com with ESMTPSA id q4sm3376728lfm.46.2020.09.16.13.06.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2020 13:06:20 -0700 (PDT) From: mateusznosek0@gmail.com To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Mateusz Nosek , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org Subject: [PATCH] mm/slab.c: micro-optimization spare one branch in main flow Date: Wed, 16 Sep 2020 22:05:39 +0200 Message-Id: <20200916200539.23268-1-mateusznosek0@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mateusz Nosek By small refactoring two 'unlikely' branches are changed so that if not one of them is true then only one branch occurs in 'likely' path of the function in question. Change verified in assembly generated by gcc 8.3.0. Signed-off-by: Mateusz Nosek --- mm/slab.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 2cb494d98fe9..e04ea756bcbc 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -4186,9 +4186,10 @@ size_t __ksize(const void *objp) struct kmem_cache *c; size_t size; - BUG_ON(!objp); - if (unlikely(objp == ZERO_SIZE_PTR)) + if (unlikely(ZERO_OR_NULL_PTR(objp))) { + BUG_ON(!objp); return 0; + } c = virt_to_cache(objp); size = c ? c->object_size : 0; -- 2.20.1