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 62496C54FCC for ; Tue, 21 Apr 2020 15:16:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 422D5206D9 for ; Tue, 21 Apr 2020 15:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587482162; bh=uklg+mgdxavZLV9+AiizuXXNfarJAGtL7/umiBXuknU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2aty6nkIh4/ajp86EUBauxZ+vdhFmFp2s8kFai5HhwPqqOQ4B2nyl/sAK3iZ51uTS ZqEZjbpZZqFXbx9OZs52USQApXftL3qk9/0mhZOp5SKMt5HI/NpB02XLxDmWgnY058 sYr2DkheGXuZYHX6d8AScYFef8OX/6sW4sTE6bbo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727023AbgDUPQB (ORCPT ); Tue, 21 Apr 2020 11:16:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:34834 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726688AbgDUPP5 (ORCPT ); Tue, 21 Apr 2020 11:15:57 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [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 85933206D9; Tue, 21 Apr 2020 15:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587482157; bh=uklg+mgdxavZLV9+AiizuXXNfarJAGtL7/umiBXuknU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dtXWGwjz6I5F+kGQ68k8ayw0bI65bZkP8kaAXCi7THCQM0ukdXRHZFQ5nt3vugjHP JTXFMatja5sk2QZwu5bcp5B7kZ5jF4h5S1YzFiIRYfc4nCPITF+uSbS2SV/P/+6Fin IpsAHA5kZmqqwLGJUw4Wn18mTeQlp2dujZroH6FM= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-team@android.com, Will Deacon , Mark Rutland , 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 v4 04/11] fault_inject: Don't rely on "return value" from WRITE_ONCE() Date: Tue, 21 Apr 2020 16:15:30 +0100 Message-Id: <20200421151537.19241-5-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200421151537.19241-1-will@kernel.org> References: <20200421151537.19241-1-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; -- 2.26.1.301.g55bc3eb7cb9-goog