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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 21C91C43603 for ; Wed, 18 Dec 2019 17:47:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0FEB21582 for ; Wed, 18 Dec 2019 17:47:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="wFMRrqMs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727031AbfLRRr2 (ORCPT ); Wed, 18 Dec 2019 12:47:28 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:40117 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726985AbfLRRr2 (ORCPT ); Wed, 18 Dec 2019 12:47:28 -0500 Received: by mail-pl1-f195.google.com with SMTP id g6so1290596plp.7 for ; Wed, 18 Dec 2019 09:47:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=oIE/497lOI7LXc9jgu4fcSd10UVgyYO9WDSbuj+M5ig=; b=wFMRrqMsTXCYjfDjvWyZohde2LR/IevgpQJF96FF6Eb1BeaG44rQelM2V2uJH0kX31 tmy8KVdBRh/vLeJtwdEOVP72KkmXfL/aTACuSkf4oXfLIaoNVSRU3U3lf59Rq/pdNSw4 zI6uprq3bmbWl4WAXYL+5x8a+o5L/AVBifW3RPuuXmORdJN3xpERd7FSIxFaBh8iLi3h ChEOvBbl1eAH/a+FSzSH7JktEFYDGQyvKE8Go432aX4FvqUlIEGh3rIMHK4hmBy4+vtQ 9K5HS/hVh9lXt2KvqR2Wxe8Y9/0gBx/sjzb3ulqSJC3RKY/Q5gtUD6KaqiYQfOAqRHMX cq3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=oIE/497lOI7LXc9jgu4fcSd10UVgyYO9WDSbuj+M5ig=; b=sS/52sPH+SwO+RLtYumvzNpvLc3cdCB3pTxkqHZHRT6kknr+6s+iiyEc4zC/jhh5gC Zjz1Li2EDjlWoY2kjB3iIJxp3P81Kyiaoq9PKEMdlwHxQiDGEqWyeTs0BOwPemeqfoHo 8C/w8aRDenWvDZW7e5SO2qjXjuPVnbparfbRVHUp3LqFPTk3D/Lm3LbPuYf6H8ojBGgv QZvcTLMBaEexWWeiEqnp5diGdITLILOBrG0+cIdXrTyyNLu6yXxmrS+pDcnshts9OFKj X9a+C44XWN72aeDU0v5lc9hVZa/Hbhcfaydl9VWT/5TSubQVTL0Dl89W5zAA0cKmgayn rlYA== X-Gm-Message-State: APjAAAWJm87ZNTyHy2py+HWDs5pkvQ8V9aWah0pU9VN0vx0tV8OdiGMA okmPH+6OL4WaKvvQhcwr2fDxgQ== X-Google-Smtp-Source: APXvYqzrW1Ni4SADZX2cj4+UeYnZzyfvgqMwNH562anPy2ilqN4FNH/QwSxO2WTiRWGpevJElK4Xxw== X-Received: by 2002:a17:90a:974a:: with SMTP id i10mr4410453pjw.0.1576691247884; Wed, 18 Dec 2019 09:47:27 -0800 (PST) Received: from cakuba.netronome.com ([2601:646:8e00:e18::5]) by smtp.gmail.com with ESMTPSA id a10sm4021874pgm.81.2019.12.18.09.47.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Dec 2019 09:47:27 -0800 (PST) Date: Wed, 18 Dec 2019 09:47:23 -0800 From: Jakub Kicinski To: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , bpf@vger.kernel.org, davem@davemloft.net, hawk@kernel.org, john.fastabend@gmail.com, magnus.karlsson@intel.com, jonathan.lemon@gmail.com Subject: Re: [PATCH bpf-next 2/8] xdp: simplify cpumap cleanup Message-ID: <20191218094723.13ab0d54@cakuba.netronome.com> In-Reply-To: <20191218105400.2895-3-bjorn.topel@gmail.com> References: <20191218105400.2895-1-bjorn.topel@gmail.com> <20191218105400.2895-3-bjorn.topel@gmail.com> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, 18 Dec 2019 11:53:54 +0100, Bj=C3=B6rn T=C3=B6pel wrote: > From: Bj=C3=B6rn T=C3=B6pel >=20 > After the RCU flavor consolidation [1], call_rcu() and > synchronize_rcu() waits for preempt-disable regions (NAPI) in addition > to the read-side critical sections. As a result of this, the cleanup > code in cpumap can be simplified >=20 > * There is no longer a need to flush in __cpu_map_entry_free, since we > know that this has been done when the call_rcu() callback is > triggered. >=20 > * When freeing the map, there is no need to explicitly wait for a > flush. It's guaranteed to be done after the synchronize_rcu() call > in cpu_map_free(). >=20 > [1] https://lwn.net/Articles/777036/ >=20 > Signed-off-by: Bj=C3=B6rn T=C3=B6pel Probably transient but: ../kernel/bpf/cpumap.c: In function "cpu_map_free": ../kernel/bpf/cpumap.c:502:6: warning: unused variable "cpu" [-Wunused-vari= able] 502 | int cpu; | ^~~ I think there are also warnings in patch 4.