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 A7F61C2BA19 for ; Wed, 15 Apr 2020 16:53:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85CE4208FE for ; Wed, 15 Apr 2020 16:53:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586969602; bh=XpbKApHWYMc5/QzVBiMD1ies30gMGiNifJYoWGWxCgw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EuyxYHlyYE8Gwuu8quCQEVtbo97efAEUJTgMDxaiPpDv6w13lj2sbt0x4IFeSxZvg g8VCfl0D9gd5M5231ZHFULS7AU7+Lk5ew7W8is+icIOZIJo6zASc4/iD4piMfV87rx ya0jKa65q7lrivGnQLd1sApeZ+MW493Cp8ChGlAg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410538AbgDOQxV (ORCPT ); Wed, 15 Apr 2020 12:53:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:54892 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2410496AbgDOQxA (ORCPT ); Wed, 15 Apr 2020 12:53:00 -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 1CE4820857; Wed, 15 Apr 2020 16:52:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586969580; bh=XpbKApHWYMc5/QzVBiMD1ies30gMGiNifJYoWGWxCgw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vE6Qg9+U9QSoa/pH3npc1gJMA7o/Z0/taFmWB2Xwep44SEXhrR+m9/SJr/xickOPs NHdHB7hnR8Ur/oxMG7SK18wPe3l8IJf1aZIOUDRINncA8smrujVm0IIk4Hj11Xcgpt rrAo42qgZo/WQT3OrkNrZ0d//yzMVHBBGgYGyxXA= 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 , Akinobu Mita Subject: [PATCH v3 04/12] fault_inject: Don't rely on "return value" from WRITE_ONCE() Date: Wed, 15 Apr 2020 17:52:10 +0100 Message-Id: <20200415165218.20251-5-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 It's a bit weird that WRITE_ONCE() evaluates to the value it stores and it's different to smp_store_release(), which can't be used this way. In preparation for preventing this in WRITE_ONCE(), change the fault injection code to use a local variable instead. Cc: Akinobu Mita Signed-off-by: Will Deacon --- lib/fault-inject.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/fault-inject.c b/lib/fault-inject.c index 8186ca84910b..ce12621b4275 100644 --- a/lib/fault-inject.c +++ b/lib/fault-inject.c @@ -106,7 +106,9 @@ bool should_fail(struct fault_attr *attr, ssize_t size) unsigned int fail_nth = READ_ONCE(current->fail_nth); if (fail_nth) { - if (!WRITE_ONCE(current->fail_nth, fail_nth - 1)) + fail_nth--; + WRITE_ONCE(current->fail_nth, fail_nth); + if (!fail_nth) goto fail; return false; -- 2.26.0.110.g2183baf09c-goog