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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8BA1C2BA19 for ; Wed, 15 Apr 2020 16:53:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 855BD214AF for ; Wed, 15 Apr 2020 16:53:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586969619; bh=B8R3GsZsbA6fc0Q2WUcNbOSuFs4/13y9+Ju2qwpXvr0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=y+tdpOO1wUBpJzRDlikN9ddCtBh4rzGwMBVgsX8wGhwvY15ToW0sR5/kTl7dCmjnd zCTp2FADURgG6a168G4ji76Ge5TEi3FMYYAZ99kTzyKQ+DQp5Z6oRQzdG5CoN9UA2W 0nNIXtzP/GfB21VgtMcOkm1YqOXFZ372HaU6FrK4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410575AbgDOQxi (ORCPT ); Wed, 15 Apr 2020 12:53:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:55230 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2410521AbgDOQxO (ORCPT ); Wed, 15 Apr 2020 12:53:14 -0400 Received: from localhost.localdomain (unknown [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 151F2208FE; Wed, 15 Apr 2020 16:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586969594; bh=B8R3GsZsbA6fc0Q2WUcNbOSuFs4/13y9+Ju2qwpXvr0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w4oWkOi0kLClBEHQjHG3WajKCp8buLF0JLbgbwOxCILRvVrP4mJTrGzh6oUVlyOmV LprQLMHKIa81ksAogvRLv7h+6y/lp2N9EH3pTD1jYdBLCKAy2KhaH1c3hEL2ETCDrK Spb/O20lLc2Ts+49sOtQH4FMI/ijBVAbqdCM7Tiw= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-team@android.com, Will Deacon , Michael Ellerman , Peter Zijlstra , Linus Torvalds , Segher Boessenkool , Christian Borntraeger , Luc Van Oostenryck , Arnd Bergmann , Peter Oberparleiter , Masahiro Yamada , Nick Desaulniers Subject: [PATCH v3 09/12] locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros Date: Wed, 15 Apr 2020 17:52:15 +0100 Message-Id: <20200415165218.20251-10-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200415165218.20251-1-will@kernel.org> References: <20200415165218.20251-1-will@kernel.org> 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 Passing volatile-qualified pointers to the asm-generic implementations of the load-acquire macros results in a re-load from the stack due to the temporary result variable inheriting the volatile semantics thanks to the use of 'typeof()'. Define these temporary variables using 'unqual_scalar_typeof' to drop the volatile qualifier in the case that they are scalar types. Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Arnd Bergmann Signed-off-by: Will Deacon --- include/asm-generic/barrier.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 85b28eb80b11..2eacaf7d62f6 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -128,10 +128,10 @@ do { \ #ifndef __smp_load_acquire #define __smp_load_acquire(p) \ ({ \ - typeof(*p) ___p1 = READ_ONCE(*p); \ + __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ compiletime_assert_atomic_type(*p); \ __smp_mb(); \ - ___p1; \ + (typeof(*p))___p1; \ }) #endif @@ -183,10 +183,10 @@ do { \ #ifndef smp_load_acquire #define smp_load_acquire(p) \ ({ \ - typeof(*p) ___p1 = READ_ONCE(*p); \ + __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ compiletime_assert_atomic_type(*p); \ barrier(); \ - ___p1; \ + (typeof(*p))___p1; \ }) #endif @@ -229,14 +229,14 @@ do { \ #ifndef smp_cond_load_relaxed #define smp_cond_load_relaxed(ptr, cond_expr) ({ \ typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ + __unqual_scalar_typeof(*ptr) VAL; \ for (;;) { \ VAL = READ_ONCE(*__PTR); \ if (cond_expr) \ break; \ cpu_relax(); \ } \ - VAL; \ + (typeof(*ptr))VAL; \ }) #endif @@ -250,10 +250,10 @@ do { \ */ #ifndef smp_cond_load_acquire #define smp_cond_load_acquire(ptr, cond_expr) ({ \ - typeof(*ptr) _val; \ + __unqual_scalar_typeof(*ptr) _val; \ _val = smp_cond_load_relaxed(ptr, cond_expr); \ smp_acquire__after_ctrl_dep(); \ - _val; \ + (typeof(*ptr))_val; \ }) #endif -- 2.26.0.110.g2183baf09c-goog