From patchwork Fri Dec 11 17:45:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Ivanov X-Patchwork-Id: 1415173 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2001:8b0:10b:1231::1; helo=merlin.infradead.org; envelope-from=linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=cambridgegreys.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; secure) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=merlin.20170209 header.b=ICCHPY/s; dkim-atps=neutral Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4Csyry4rlfz9sSf for ; Sat, 12 Dec 2020 04:46:42 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Ce3nKtouTt3aKAOid49D51qOla7LZ0AXSN81fKeLorY=; b=ICCHPY/s7AFAt/qxe7TXIcKvw YzIjS29My3veo8ek6q2CTntITnWJVU0C6mwgYBKqWpCUsj41l8XhnxhP6nlhtH372JOSlrPVrVAWZ xdAMAYRShVgeP9bJRGteTvL23HZNuoAlh7QG4IcSEghCVDZRVILgcCNDwVpoWvyCvJ1xNfWHoUFDV Wic9hfD7zcK+tYWAiz8fKYv1wcCKnMo5fv409R/mOIznUJ2pWy2n1LRUWJYw8OqugMsI0Ny/PlsaH 8/Y6qNPXai3RsMtUooS87sWX2QQtSYsEgdUxJcGjI/C98eQ6RAg3lmtp0quz1rBEUKUVOtueKA1+Q T61LIWYjg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1knmUx-0008KS-Fo; Fri, 11 Dec 2020 17:46:31 +0000 Received: from ivanoab7.miniserver.com ([37.128.132.42] helo=www.kot-begemot.co.uk) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1knmUt-0008IV-40 for linux-um@lists.infradead.org; Fri, 11 Dec 2020 17:46:27 +0000 Received: from tun252.jain.kot-begemot.co.uk ([192.168.18.6] helo=jain.kot-begemot.co.uk) by www.kot-begemot.co.uk with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1knmUs-00020H-AQ; Fri, 11 Dec 2020 17:46:26 +0000 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by jain.kot-begemot.co.uk with esmtp (Exim 4.92) (envelope-from ) id 1knmUp-0006zn-Mb; Fri, 11 Dec 2020 17:46:25 +0000 From: anton.ivanov@cambridgegreys.com To: linux-um@lists.infradead.org Subject: [PATCH v4 6/7] um: swithch futex ops to cmpxchg Date: Fri, 11 Dec 2020 17:45:58 +0000 Message-Id: <20201211174559.26010-7-anton.ivanov@cambridgegreys.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201211174559.26010-1-anton.ivanov@cambridgegreys.com> References: <20201211174559.26010-1-anton.ivanov@cambridgegreys.com> MIME-Version: 1.0 X-Spam-Score: -1.0 X-Spam-Score: -1.0 X-Clacks-Overhead: GNU Terry Pratchett X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201211_124627_233420_E6DAD137 X-CRM114-Status: UNSURE ( 9.25 ) X-CRM114-Notice: Please train this message. X-Spam-Score: 0.4 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (0.4 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_NONE SPF: sender does not publish an SPF Record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.4 KHOP_HELO_FCRDNS Relay HELO differs from its IP's reverse DNS X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: richard@nod.at, Anton Ivanov Sender: "linux-um" Errors-To: linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org From: Anton Ivanov As a result of switching from emulated to true atomic cmpxchg we can use cmpxchg in the corresponding um futex op. Signed-off-by: Anton Ivanov --- arch/um/kernel/skas/uaccess.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c index de71048b5371..858b2e16e364 100644 --- a/arch/um/kernel/skas/uaccess.c +++ b/arch/um/kernel/skas/uaccess.c @@ -343,7 +343,6 @@ EXPORT_SYMBOL(arch_futex_atomic_op_inuser); * -EAGAIN - Atomic operation was unable to complete due to contention * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG) */ - int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, u32 newval) { @@ -366,8 +365,7 @@ int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, val = *uaddr; - if (val == oldval) - *uaddr = newval; + ret = cmpxchg(uaddr, oldval, newval); *uval = val; pagefault_enable();