From nobody Mon Apr 6 01:41:39 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9959C54EE9 for ; Tue, 13 Sep 2022 18:11:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232491AbiIMSL4 (ORCPT ); Tue, 13 Sep 2022 14:11:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231907AbiIMSLJ (ORCPT ); Tue, 13 Sep 2022 14:11:09 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85E3A72B7C for ; Tue, 13 Sep 2022 10:18:01 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id p18so12490354plr.8 for ; Tue, 13 Sep 2022 10:18:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=XQ8hIFG6q5WKMN5Ns4E0eRv8QKNJMaYAAhMqE3kUHyU=; b=Zwd2T64CMlOt2t6v2YUv91XYfNgJbAxGmsslT3ZAOs6w6EZg8t5Fqp8Nqh8dVEKNAA FqB9RVgbnB5pAyE57yYcdPvNa3eK64heDwFxyr1qvrUFEBWY/8t5kaRgEGMu0OsOUvVk rgmlIr3av1kFrhsoQVo6gw7QSDja6eytLvufYelEZXhwBU4yEEmu36iJOPKR+NAcJx6R UDEu5dpNkDEBF3pPNPSxZTIce6cEgmE6LsXYTBHQXL8MNOnp2+etsTirEjdR8SZnElid DzmhxcVu6uxPtGGYRT57qjG2E7JL8PUIeaqgsNR5nSimhHdOf0kfcFDwQ3j+5j9EWE+Z Y2fA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=XQ8hIFG6q5WKMN5Ns4E0eRv8QKNJMaYAAhMqE3kUHyU=; b=XxrJ6qYEl45KiIfTPAbw1U9jhfKtyl5eudoSoUhsDWEwt1S49P3Wo1uMkVidSO3aer fLiATzUYV5BUwVgxDhCQOVotfO/xfvucUGj8juVF1cdIrmjXsizQ0FdWdxy8f+aZkJdE VLBNt8KGvNWxeLzpEWHqJFkru/jt2o1ijlmb5sgg049LLJHXo9F8f1IvqQ1V/crjBtmn 2rGcu/FHoZ9VRtFSH6lcuhdTzeAkYKNIyr3Ms0PymnqCoivZ7sdzjRLaS93Wa3UIAWXL yl4+83FD9Mo9u5ZMKf5p50BDvdAsjGAo8/P9eDnld9E8Mf3ZpbeCzttapy3BHnbTjIzT MAVw== X-Gm-Message-State: ACgBeo0srT7kzo5ptrJGIRxObhf0uUMonX3eHLjs7ge2GolXsP+9u6Wj j/CBJsfxF7bzMQIJJpcMnRiKcpukz6X/3w== X-Google-Smtp-Source: AA6agR6R65XTgekQohxDq76X9er4kMYytxvwLwcHqbE3PUPmsCOvUZYFcycYI1IHpgWbWwLDaTiQlw== X-Received: by 2002:a17:902:820a:b0:178:456e:138 with SMTP id x10-20020a170902820a00b00178456e0138mr4704863pln.145.1663089480839; Tue, 13 Sep 2022 10:18:00 -0700 (PDT) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id z27-20020aa79e5b000000b0053e5b905843sm796474pfq.203.2022.09.13.10.17.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Sep 2022 10:18:00 -0700 (PDT) From: Nadav Amit X-Google-Original-From: Nadav Amit To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, VMware PV-Drivers Reviewers , Arnd Bergmann , Nadav Amit Subject: [PATCH 1/3] vmw_balloon: access reset_required through READ/WRITE_ONCE Date: Tue, 13 Sep 2022 02:43:04 -0700 Message-Id: <20220913094306.317734-2-namit@vmware.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220913094306.317734-1-namit@vmware.com> References: <20220913094306.317734-1-namit@vmware.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Nadav Amit reset_required might be accessed concurrently, at least through debugfs. While there is no apparent functional risk, avoid any potential race, even if it is benign. Use READ_ONCE() and WRITE_ONCE() when accessing reset_required. Signed-off-by: Nadav Amit --- drivers/misc/vmw_balloon.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index 61a2be712bf7..7fa91983c567 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -492,7 +492,7 @@ __vmballoon_cmd(struct vmballoon *b, unsigned long cmd,= unsigned long arg1, =20 /* mark reset required accordingly */ if (status =3D=3D VMW_BALLOON_ERROR_RESET) - b->reset_required =3D true; + WRITE_ONCE(b->reset_required, true); =20 return status; } @@ -965,7 +965,7 @@ static int64_t vmballoon_change(struct vmballoon *b) * Otherwise we might get huge positives instead of negatives */ =20 - if (b->reset_required) + if (READ_ONCE(b->reset_required)) return 0; =20 /* consider a 2MB slack on deflate, unless the balloon is emptied */ @@ -1446,7 +1446,7 @@ static void vmballoon_reset(struct vmballoon *b) } =20 vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_RESET); - b->reset_required =3D false; + WRITE_ONCE(b->reset_required, false); =20 error =3D vmballoon_vmci_init(b); if (error) @@ -1473,7 +1473,7 @@ static void vmballoon_work(struct work_struct *work) struct vmballoon *b =3D container_of(dwork, struct vmballoon, dwork); int64_t change =3D 0; =20 - if (b->reset_required) + if (READ_ONCE(b->reset_required)) vmballoon_reset(b); =20 down_read(&b->conf_sem); @@ -1666,7 +1666,7 @@ static int vmballoon_debug_show(struct seq_file *f, v= oid *offset) VMW_BALLOON_CAPABILITIES); seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities); seq_printf(f, "%-22s: %16s\n", "is resetting", - b->reset_required ? "y" : "n"); + READ_ONCE(b->reset_required) ? "y" : "n"); =20 /* format size info */ seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target)); --=20 2.25.1