From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EE51CCA481 for ; Tue, 28 Jun 2022 08:19:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242607AbiF1ITQ (ORCPT ); Tue, 28 Jun 2022 04:19:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243895AbiF1IS5 (ORCPT ); Tue, 28 Jun 2022 04:18:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17B3727FE5; Tue, 28 Jun 2022 01:17:28 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C7E51B81C0F; Tue, 28 Jun 2022 08:17:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 532B8C341CB; Tue, 28 Jun 2022 08:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1656404245; bh=wuMCLxNzxYSmxOh5v/SBPcUTtvTDqjGgAdULUenQIXg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pPb+/fENqMFaNUkZi6ql3d0fdSuDA7WTP/Lpo5BBmMl376GJTJ5wk6oq5bjBKJujt AUAkSyTrMojK8B6lta+rMW/hVbpHJ4EbCDBZ3s1u2HDX6r9aytN5JiiJVFIfKbSUVJ MDsa4DdyVpOAxrwZre4pbBxEtJENcdfdbbsl9zJETI27O4EeiRcHd5ox2nguiOMi57 7swCaCeIbQK/SbiHBmRrq/8mj7XWoj0oMDQfLt/ldfv4beWX37ef27Zq27Hh9ugOtg 9n1Ut6VjS0R+FmzLF8AhoEfAsSOtt/Dcz0LJCEAhgal1ah9yWzcfIo1IDAIzhgeCFi KH3mqQj9ea+aw== From: guoren@kernel.org To: palmer@rivosinc.com, arnd@arndb.de, mingo@redhat.com, will@kernel.org, longman@redhat.com, boqun.feng@gmail.com Cc: linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Guo Ren , Guo Ren , Peter Zijlstra Subject: [PATCH V7 1/5] asm-generic: ticket-lock: Remove unnecessary atomic_read Date: Tue, 28 Jun 2022 04:17:03 -0400 Message-Id: <20220628081707.1997728-2-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220628081707.1997728-1-guoren@kernel.org> References: <20220628081707.1997728-1-guoren@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org From: Guo Ren Remove unnecessary atomic_read in arch_spin_value_unlocked(lock), because the value has been in lock. This patch could prevent arch_spin_value_unlocked contend spin_lock data again. Signed-off-by: Guo Ren Signed-off-by: Guo Ren Cc: Peter Zijlstra (Intel) Cc: Arnd Bergmann Cc: Palmer Dabbelt --- include/asm-generic/spinlock.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/spinlock.h b/include/asm-generic/spinlock.h index fdfebcb050f4..f1e4fa100f5a 100644 --- a/include/asm-generic/spinlock.h +++ b/include/asm-generic/spinlock.h @@ -84,7 +84,9 @@ static __always_inline int arch_spin_is_contended(arch_spinlock_t *lock) static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) { - return !arch_spin_is_locked(&lock); + u32 val = lock.counter; + + return ((val >> 16) == (val & 0xffff)); } #include -- 2.36.1