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=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 ACD90C5519F for ; Fri, 20 Nov 2020 11:37:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C29E22253 for ; Fri, 20 Nov 2020 11:37:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="VXyEdkDX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727254AbgKTLg0 (ORCPT ); Fri, 20 Nov 2020 06:36:26 -0500 Received: from z5.mailgun.us ([104.130.96.5]:18504 "EHLO z5.mailgun.us" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726123AbgKTLg0 (ORCPT ); Fri, 20 Nov 2020 06:36:26 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1605872185; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=WN5oSJatZKvg9t0/CJOWr+ndW71BqBE1aHw3x3obRKA=; b=VXyEdkDXAdwAwkoixe3cXDig/TwOhzfNBviOtAQUkTGo6bbs/fFn5j1+WRMPmvWgM6pR7uSG 81ryulAbGBMDo14/k1oiwpdchLNzF5vZxlb1YQac4krDaUQH1XSneDSBASBjwjl64xwoqTmz hDyNP/Le5DLQFP3tN7p6AzsD6d8= 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-n03.prod.us-west-2.postgun.com with SMTP id 5fb7aa371dba509aaead1a2c (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 20 Nov 2020 11:36:23 GMT Sender: neeraju=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 8ACE0C433C6; Fri, 20 Nov 2020 11:36:23 +0000 (UTC) Received: from [192.168.0.101] (unknown [124.123.182.78]) (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 3CC94C433ED; Fri, 20 Nov 2020 11:36:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 3CC94C433ED 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 RFC tip/core/rcu 2/5] srcu: Provide internal interface to start a Tiny SRCU grace period To: paulmck@kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, rcu@vger.kernel.org References: <20201117004017.GA7444@paulmck-ThinkPad-P72> <20201117004052.14758-2-paulmck@kernel.org> From: Neeraj Upadhyay Message-ID: Date: Fri, 20 Nov 2020 17:06:13 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.3 MIME-Version: 1.0 In-Reply-To: <20201117004052.14758-2-paulmck@kernel.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 11/17/2020 6:10 AM, paulmck@kernel.org wrote: > From: "Paul E. McKenney" > > There is a need for a polling interface for SRCU grace periods. > This polling needs to initiate an SRCU grace period without > having to queue (and manage) a callback. This commit therefore > splits the Tiny SRCU call_srcu() function into callback-queuing and > start-grace-period portions, with the latter in a new function named > srcu_gp_start_if_needed(). > > Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/ > Reported-by: Kent Overstreet > Signed-off-by: Paul E. McKenney > --- Reviewed-by: Neeraj Upadhyay Thanks Neeraj > kernel/rcu/srcutiny.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c > index 5598cf6..3bac1db 100644 > --- a/kernel/rcu/srcutiny.c > +++ b/kernel/rcu/srcutiny.c > @@ -152,6 +152,16 @@ void srcu_drive_gp(struct work_struct *wp) > } > EXPORT_SYMBOL_GPL(srcu_drive_gp); > > +static void srcu_gp_start_if_needed(struct srcu_struct *ssp) > +{ > + if (!READ_ONCE(ssp->srcu_gp_running)) { > + if (likely(srcu_init_done)) > + schedule_work(&ssp->srcu_work); > + else if (list_empty(&ssp->srcu_work.entry)) > + list_add(&ssp->srcu_work.entry, &srcu_boot_list); > + } > +} > + > /* > * Enqueue an SRCU callback on the specified srcu_struct structure, > * initiating grace-period processing if it is not already running. > @@ -167,12 +177,7 @@ void call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp, > *ssp->srcu_cb_tail = rhp; > ssp->srcu_cb_tail = &rhp->next; > local_irq_restore(flags); > - if (!READ_ONCE(ssp->srcu_gp_running)) { > - if (likely(srcu_init_done)) > - schedule_work(&ssp->srcu_work); > - else if (list_empty(&ssp->srcu_work.entry)) > - list_add(&ssp->srcu_work.entry, &srcu_boot_list); > - } > + srcu_gp_start_if_needed(ssp); > } > EXPORT_SYMBOL_GPL(call_srcu); > > -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation