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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7334CC433C1 for ; Mon, 29 Mar 2021 05:51:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4766161927 for ; Mon, 29 Mar 2021 05:51:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231708AbhC2FvR (ORCPT ); Mon, 29 Mar 2021 01:51:17 -0400 Received: from wout4-smtp.messagingengine.com ([64.147.123.20]:36649 "EHLO wout4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230161AbhC2Fur (ORCPT ); Mon, 29 Mar 2021 01:50:47 -0400 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.west.internal (Postfix) with ESMTP id 7676A11E7; Mon, 29 Mar 2021 01:50:46 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Mon, 29 Mar 2021 01:50:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm3; bh=NfxygTjF21CkAar3h4Buj9dNcp2 7qlZSFcwGrlo/1BI=; b=d1DbWZTJiOIh2jV0okhs/husEz7KmtTzCk8T0D/7945 mPmrhPtAIYLAXLOVBfOfGhFWYJKS0mNtJui4G5/7HKXMEK+w29/LmRFaom/d0+Q6 dcrZAU4JZERPzmOb7PaStSdiNJExRMEpqp+pmDlj5XCnvXNsCIFARMWyxy3Y8o0U XwdiDKG19OJvQTLTC2V7qKfKuMvTKzfvLTrWOnH3PPU9rp3TAGgyUoCzNOLMhS3D djL8e7oytVijFB14rOaGuNc+CQEA/h21okQ0RRZbCq2JxKiRXhDFFa8faysvUGWr xzIm4JAEt5OCS7AHQw5wDgNPqwEbwnkAXg/s0dbSTQQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=NfxygT jF21CkAar3h4Buj9dNcp27qlZSFcwGrlo/1BI=; b=jhq82gNOPxtexf73CAJHo7 zZphbKI2sJNwvTBFzKPPtRjAYGpD9CrbJ+XplJXsA9Qim8pd45SvbK5aeZWSi/Vj /BfqQOF7tlN857hB+bEVSUypet0qpNIvuuQ0LHyD34HaCm55au9fPXKXKTIedoIa TI4ejfQdE6KZJkPBgqprAEYjp2Sy/qf79jqIGxRMAYSlBC3pBGktf8SACKzuZXme k2WJy/52R/MdUShhdRTryqxh0MATkIhe2JYxpEaFlbRqi6ZBnZFGkURlAic8na1N pAkIDiQ9Hjq8Clu80B5t7zMQQJKm6MCILYFSS5MdQlQG1+CHty0KMaZ55meUXmHQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrudehjedgleelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucggtffrrghtthgvrhhnpeeuleeltd ehkeeltefhleduuddvhfffuedvffduveegheekgeeiffevheegfeetgfenucffohhmrghi nhepkhgvrhhnvghlrdhorhhgnecukfhppeekfedrkeeirdejgedrieegnecuvehluhhsth gvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghh rdgtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 56D6A24005B; Mon, 29 Mar 2021 01:50:45 -0400 (EDT) Date: Mon, 29 Mar 2021 07:50:43 +0200 From: Greg KH To: Ben Hutchings Cc: stable@vger.kernel.org, Lee Jones , "Luis Claudio R. Goncalves" , Florian Fainelli Subject: Re: [PATCH 01/13] futex: Use smp_store_release() in mark_wake_futex() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sun, Mar 28, 2021 at 10:40:54PM +0200, Ben Hutchings wrote: > From: Peter Zijlstra > > commit 1b367ece0d7e696cab1c8501bab282cc6a538b3f upstream. > > Since the futex_q can dissapear the instruction after assigning NULL, > this really should be a RELEASE barrier. That stops loads from hitting > dead memory too. > > Signed-off-by: Peter Zijlstra (Intel) > Cc: juri.lelli@arm.com > Cc: bigeasy@linutronix.de > Cc: xlpang@redhat.com > Cc: rostedt@goodmis.org > Cc: mathieu.desnoyers@efficios.com > Cc: jdesfossez@efficios.com > Cc: dvhart@infradead.org > Cc: bristot@redhat.com > Link: http://lkml.kernel.org/r/20170322104151.604296452@infradead.org > Signed-off-by: Thomas Gleixner > Signed-off-by: Ben Hutchings > --- > kernel/futex.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/futex.c b/kernel/futex.c > index 796b1c860839..e112a9d4c84f 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -1565,8 +1565,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) > * memory barrier is required here to prevent the following > * store to lock_ptr from getting ahead of the plist_del. > */ > - smp_wmb(); > - q->lock_ptr = NULL; > + smp_store_release(&q->lock_ptr, NULL); > } > > /* > All now queued up, thanks. greg k-h