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 59D7BC282DD for ; Fri, 10 Jan 2020 16:56:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2584D2072A for ; Fri, 10 Jan 2020 16:56:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578675413; bh=135J+SSbyQIAXby29osr73Ejb0gbQ2jsQHGnN98q/YM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JCfFB1frg26vCXFC04M6LbweKZ0/pYEhUTxs/4/Dminr4lQvLDv6jqDU96GdTi3v9 P+VvERqCewf1mWRLAPqneFcZrOs1Ua6TQspEpdFPIErFsUTEYeA4jDHETAfIYSFTIX hnG3cUtWPDefv3FmFla7HVRssW+4gJ9LQ2KAI1GY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728678AbgAJQ4w (ORCPT ); Fri, 10 Jan 2020 11:56:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:60112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728594AbgAJQ4u (ORCPT ); Fri, 10 Jan 2020 11:56:50 -0500 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 D4BFA2072E; Fri, 10 Jan 2020 16:56:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578675409; bh=135J+SSbyQIAXby29osr73Ejb0gbQ2jsQHGnN98q/YM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=He2XFOmKXv4Q9/l2imLkHmPFwEHXREZbY98P5xTPghu6u6GNU03Tn8ZEUBLgd68m9 e1Ns8tF5aEwCFAjMmX5sgNlFsejRJbP65wBUi0Qq6z+yoLcoW7SIZmsxMjOh1MOcY/ DZSwnMe2a6deePG2j8EDW3ljbV4O6TbIKWC+QnXs= 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 , Akinobu Mita Subject: [RFC PATCH 3/8] fault_inject: Don't rely on "return value" from WRITE_ONCE() Date: Fri, 10 Jan 2020 16:56:31 +0000 Message-Id: <20200110165636.28035-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200110165636.28035-1-will@kernel.org> References: <20200110165636.28035-1-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; -- 2.25.0.rc1.283.g88dfdc4193-goog