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=-11.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 81BA2C2D0A3 for ; Wed, 4 Nov 2020 13:38:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B4C922243 for ; Wed, 4 Nov 2020 13:38:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="nLHF1YAV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729520AbgKDNiQ (ORCPT ); Wed, 4 Nov 2020 08:38:16 -0500 Received: from z5.mailgun.us ([104.130.96.5]:45369 "EHLO z5.mailgun.us" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729584AbgKDNiP (ORCPT ); Wed, 4 Nov 2020 08:38:15 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1604497095; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=RxrPn8ohTBs9IISAW9lDtPNqPK2tcUCvIx4y39dCtjI=; b=nLHF1YAVyCYMg4/pxHXsO0QU/IgkJlLH/7/vdzkRQ6TwAcwHGcJnYnpwJhv+6CmAvffR3wTl pJnw0kxm+IHbFhuRHUektEiAy6quT7aBugyT04O+FNRfOWsosPGWWs3VtuJnpROPvXEMQjnA 5ZR3RTGfWchsLmfoZ0ts98iIOuU= X-Mailgun-Sending-Ip: 104.130.96.5 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n05.prod.us-east-1.postgun.com with SMTP id 5fa2aebaedd210180f981e62 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 04 Nov 2020 13:38:02 GMT Sender: neeraju=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 71A6BC433C6; Wed, 4 Nov 2020 13:38:01 +0000 (UTC) Received: from [192.168.0.103] (unknown [124.123.167.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: neeraju) by smtp.codeaurora.org (Postfix) with ESMTPSA id BF36AC433C8; Wed, 4 Nov 2020 13:37:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org BF36AC433C8 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=neeraju@codeaurora.org Subject: Re: [PATCH v9 3/7] srcu: Fix invoke_rcu_callbacks() segcb length adjustment To: "Joel Fernandes (Google)" , linux-kernel@vger.kernel.org Cc: Frederic Weisbecker , Josh Triplett , Lai Jiangshan , Marco Elver , Mathieu Desnoyers , "Paul E. McKenney" , rcu@vger.kernel.org, Steven Rostedt , "Uladzislau Rezki (Sony)" , fweisbec@gmail.com, neeraj.iitr10@gmail.com References: <20201103142603.1302207-1-joel@joelfernandes.org> <20201103142603.1302207-4-joel@joelfernandes.org> From: Neeraj Upadhyay Message-ID: <5fd2a2cc-71eb-e557-8cde-5dc0e166396f@codeaurora.org> Date: Wed, 4 Nov 2020 19:07:53 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201103142603.1302207-4-joel@joelfernandes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/3/2020 7:55 PM, Joel Fernandes (Google) wrote: > With earlier patches, the negative counting of the unsegmented list > cannot be used to adjust the segmented one. To fix this, sample the > unsegmented length in advance, and use it after CB execution to adjust > the segmented list's length. > > Reviewed-by: Frederic Weisbecker > Suggested-by: Frederic Weisbecker > Signed-off-by: Joel Fernandes (Google) > --- Reviewed-by: Neeraj Upadhyay > kernel/rcu/srcutree.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index 0f23d20d485a..79b7081143a7 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -1160,6 +1160,7 @@ static void srcu_advance_state(struct srcu_struct *ssp) > */ > static void srcu_invoke_callbacks(struct work_struct *work) > { > + long len; > bool more; > struct rcu_cblist ready_cbs; > struct rcu_head *rhp; > @@ -1182,6 +1183,7 @@ static void srcu_invoke_callbacks(struct work_struct *work) > /* We are on the job! Extract and invoke ready callbacks. */ > sdp->srcu_cblist_invoking = true; > rcu_segcblist_extract_done_cbs(&sdp->srcu_cblist, &ready_cbs); > + len = ready_cbs.len; > spin_unlock_irq_rcu_node(sdp); > rhp = rcu_cblist_dequeue(&ready_cbs); > for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) { > @@ -1190,13 +1192,14 @@ static void srcu_invoke_callbacks(struct work_struct *work) > rhp->func(rhp); > local_bh_enable(); > } > + WARN_ON_ONCE(ready_cbs.len); > > /* > * Update counts, accelerate new callbacks, and if needed, > * schedule another round of callback invocation. > */ > spin_lock_irq_rcu_node(sdp); > - rcu_segcblist_insert_count(&sdp->srcu_cblist, &ready_cbs); > + rcu_segcblist_add_len(&sdp->srcu_cblist, -len); > (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, > rcu_seq_snap(&ssp->srcu_gp_seq)); > sdp->srcu_cblist_invoking = false; > -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation