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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 6F2D7C18DF5 for ; Tue, 20 Nov 2018 14:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2913D20831 for ; Tue, 20 Nov 2018 14:23:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qfGv+k4L" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2913D20831 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729558AbeKUAwi (ORCPT ); Tue, 20 Nov 2018 19:52:38 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:60248 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726916AbeKUAwi (ORCPT ); Tue, 20 Nov 2018 19:52:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=VhPpR1N+F+KoJID0WBZDbRBWt1UDCzoSktkWynVFxDw=; b=qfGv+k4LZaUwz4eas+SGpwEX0 NVwUN+7joG9i2lwOeIM9gfr1rNgDuuAlCoYPDeq9AGMq+VzbBkb26MqrY1dIY0g6pnPXX8H+9baTg kQEZr10IGWKrXVB3wE6eo3OO1SKuyHVWPlA5osmMzx4lKo5PixybLrkWiTBPuHsXmvhoMSoKf9gib uY9xvS4GD6fILGRahsqm82MB4BXujc7CcUPQKnfJtIbOZ+H1pdUjj8gGvRYr34iqEXuAiIuphdOoZ uHQb+i8OG2S1qtFAbR+ht8pH4Uomuqk26J6vJC3UcOZ1JHlWSWb6jG+7KHfmOGh+XjKrS2iR9N97e zgT2Agowg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gP6vk-0006sJ-HQ; Tue, 20 Nov 2018 14:23:08 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8DBF42029F87F; Tue, 20 Nov 2018 15:23:06 +0100 (CET) Date: Tue, 20 Nov 2018 15:23:06 +0100 From: Peter Zijlstra To: Frederic Weisbecker Cc: LKML , Wanpeng Li , Thomas Gleixner , Yauheni Kaliuta , Ingo Molnar , Rik van Riel Subject: Re: [PATCH 20/25] sched/kcpustat: Introduce vtime-aware kcpustat accessor Message-ID: <20181120142306.GX2131@hirez.programming.kicks-ass.net> References: <1542163569-20047-1-git-send-email-frederic@kernel.org> <1542163569-20047-21-git-send-email-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1542163569-20047-21-git-send-email-frederic@kernel.org> 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 Wed, Nov 14, 2018 at 03:46:04AM +0100, Frederic Weisbecker wrote: > +void kcpustat_cputime(struct kernel_cpustat *kcpustat, int cpu, > + u64 *user, u64 *nice, u64 *system, > + u64 *guest, u64 *guest_nice) > +{ > + struct task_struct *curr; > + struct vtime *vtime; > + int err; > + > + if (!vtime_accounting_enabled()) { > + kcpustat_cputime_raw(kcpustat, user, nice, > + system, guest, guest_nice); > + return; > + } > + > + rcu_read_lock(); > + > + do { > + curr = rcu_dereference(kcpustat->curr); Like I explained earlier; I don't think the above is correct. task_struct is itself not RCU protected. > + if (!curr) { > + kcpustat_cputime_raw(kcpustat, user, nice, > + system, guest, guest_nice); > + break; > + } > + > + vtime = &curr->vtime; > + err = kcpustat_vtime(kcpustat, vtime, cpu, user, > + nice, system, guest, guest_nice); > + } while (err == -EAGAIN); > + > + rcu_read_unlock(); > +} > + > #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */ > -- > 2.7.4 >