From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751905AbdISMoo (ORCPT ); Tue, 19 Sep 2017 08:44:44 -0400 Received: from mail-he1eur01on0108.outbound.protection.outlook.com ([104.47.0.108]:48576 "EHLO EUR01-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751823AbdISMoP (ORCPT ); Tue, 19 Sep 2017 08:44:15 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=aryabinin@virtuozzo.com; From: Andrey Ryabinin To: Dmitry Vyukov Cc: akpm@linux-foundation.org, Andrey Konovalov , tchibo@google.com, syzkaller@googlegroups.com, Mark Rutland , linux-kernel@vger.kernel.org, Andrey Ryabinin Subject: [PATCH 3/3] kcov: remove useless barrier()s Date: Tue, 19 Sep 2017 15:46:48 +0300 Message-Id: <20170919124648.28963-3-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20170919124648.28963-1-aryabinin@virtuozzo.com> References: <20170919124648.28963-1-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [195.214.232.6] X-ClientProxiedBy: HE1PR0401CA0057.eurprd04.prod.outlook.com (2603:10a6:3:19::25) To HE1PR08MB2827.eurprd08.prod.outlook.com (2603:10a6:7:2e::26) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9d5b1012-e6fa-4dd7-a9b2-08d4ff5c20fa X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(300000500095)(300135000095)(300000501095)(300135300095)(22001)(300000502095)(300135100095)(2017030254152)(300000503095)(300135400095)(201703131423075)(201703031133081)(201702281549075)(300000504095)(300135200095)(300000505095)(300135600095)(300000506095)(300135500095);SRVR:HE1PR08MB2827; 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But we don't use in_interrupt() since b274c0bb394c ("kcov: properly check if we are in an interrupt"). Now we use in_task() which handles preempt_schedule_irq() case properly, thus no barrier required. Signed-off-by: Andrey Ryabinin --- kernel/kcov.c | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/kernel/kcov.c b/kernel/kcov.c index 14cc8c1a7cad..b7fbcbef88c1 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -71,14 +71,6 @@ void notrace __sanitizer_cov_trace_pc(void) ip -= kaslr_offset(); - /* - * There is some code that runs in interrupts but for which - * in_interrupt() returns false (e.g. preempt_schedule_irq()). - * READ_ONCE()/barrier() effectively provides load-acquire wrt - * interrupts, there are paired barrier()/WRITE_ONCE() in - * kcov_ioctl_locked(). - */ - barrier(); area = t->kcov_area; /* The first word is number of subsequent PCs. */ pos = READ_ONCE(area[0]) + 1; @@ -228,8 +220,6 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, /* Cache in task struct for performance. */ t->kcov_size = kcov->size; t->kcov_area = kcov->area; - /* See comment in __sanitizer_cov_trace_pc(). */ - barrier(); WRITE_ONCE(t->kcov_mode, kcov->mode); t->kcov = kcov; kcov->t = t; -- 2.13.5