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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 B9F9BC10F14 for ; Tue, 16 Apr 2019 09:58:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D2A920675 for ; Tue, 16 Apr 2019 09:58:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="l9v9kb6I" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728908AbfDPJ6y (ORCPT ); Tue, 16 Apr 2019 05:58:54 -0400 Received: from mail.skyhub.de ([5.9.137.197]:48458 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728230AbfDPJ6y (ORCPT ); Tue, 16 Apr 2019 05:58:54 -0400 Received: from zn.tnic (p200300EC2F0D6900D0FA583685BBD9D6.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:6900:d0fa:5836:85bb:d9d6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 20EE01EC0104; Tue, 16 Apr 2019 11:58:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1555408732; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=1MZxvXYuVs+fI0+BvuKgIZlp+pBnyc+2rhlviDrQ/mE=; b=l9v9kb6IMVKKX7RToUNNfOhNALaqicCd5VUSgpddhrtlIONM20Y1muZKrI0Yhbd4Yqhbcg pYsubgA96Rb4HaM/lRKpqUEku4qdDIpSa15wmQ0iHjoSMuhcYCSrQHuyFN2VTyl1iaipHb zSfymjr+6TWV08x5sFcmCY1CaA6WKdA= Date: Tue, 16 Apr 2019 11:58:52 +0200 From: Borislav Petkov To: Cong Wang Cc: linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, Tony Luck , Thomas Gleixner Subject: Re: [PATCH 2/2] ras: close the race condition with timer Message-ID: <20190416095852.GA31772@zn.tnic> References: <20190416012001.5338-1-xiyou.wangcong@gmail.com> <20190416012001.5338-2-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190416012001.5338-2-xiyou.wangcong@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 15, 2019 at 06:20:01PM -0700, Cong Wang wrote: > cec_timer_fn() is a timer callback which reads ce_arr.array[] > and updates its decay values. Elements could be added to or > removed from this global array in parallel, although the array > itself will not grow or shrink. del_lru_elem_unlocked() uses > FULL_COUNT() as a key to find a right element to remove, > which could be affected by the parallel timer. > > Fix this by converting the mutex to a spinlock and holding it > inside the timer. > > Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector") > Cc: Tony Luck > Cc: Borislav Petkov > Cc: Thomas Gleixner > Signed-off-by: Cong Wang > --- > drivers/ras/cec.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c > index 61332c9aab5a..a82c9d08d47a 100644 > --- a/drivers/ras/cec.c > +++ b/drivers/ras/cec.c > @@ -117,7 +117,7 @@ static struct ce_array { > }; > } ce_arr; > > -static DEFINE_MUTEX(ce_mutex); > +static DEFINE_SPINLOCK(ce_lock); Nah, pls keep the simplicity here by retaining the mutex. Use a workqueue instead to queue the spring cleaning from IRQ context and then do it when back in preemptible context. Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.