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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 A9BA2C49EAF for ; Thu, 24 Jun 2021 16:06:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91C94613EC for ; Thu, 24 Jun 2021 16:06:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231633AbhFXQIq (ORCPT ); Thu, 24 Jun 2021 12:08:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:32955 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230188AbhFXQIi (ORCPT ); Thu, 24 Jun 2021 12:08:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624550779; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6wgUfE3YuyYqn3UXIkFwKI8I46axO+CjBlTP2HaYNQM=; b=H+CQFTNYFlqZ91AajQI6h6a777VAXYunpekDTPsc9LMWkdjF/ryNIZJYiPskxakOvlxBer Vh+SG7hIQJjcKnEVfRWfmVhOkSG/+X7ZY7k52PPARMLsQKPmvG+kMW0jF5ALlNEnDzy0wH A5dzy7MP5ozpLxPciXBEl+kTjpZGzcg= Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-241-G6Wuq_iXONezhOzaubbvhw-1; Thu, 24 Jun 2021 12:06:17 -0400 X-MC-Unique: G6Wuq_iXONezhOzaubbvhw-1 Received: by mail-ej1-f70.google.com with SMTP id p5-20020a17090653c5b02903db1cfa514dso2180799ejo.13 for ; Thu, 24 Jun 2021 09:06:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=6wgUfE3YuyYqn3UXIkFwKI8I46axO+CjBlTP2HaYNQM=; b=Dcr/P1UbZic7Zs8KdfaqMm0T+6inaWCDG419x2NigoQkDy3Ikz8A71inVr9OnTV9sS 5OmKVQvRaMua2xghugvwTb5hK5LkfAd5W+f4ZveFLTU3CFikkDulaHaHsHAAIN0cFzls k/Chy50e/NFtuJKwIVHWldAwKMrmYqWQP/mX03eBJjws+7hvT7/YbhQwg9ZQbVC1NDtm 6eNEO9Ll+8E0pPeyvGOT8DhpTicLvQxukaKNtUZRaEF2zwsSdFOtfJrZ2W9bANvBYMZw q6iBYEeteMgdXJMvvBpDGKLKHSNyX1CzhsNFIi+qFdruMXQz//l9QKJdD1/tjexyV2c7 NkGw== X-Gm-Message-State: AOAM531JIdfT61vezMK0aFjhO5NEhv2yLGuGOnd9GDdjto6abwE/N4bq u5Nxa5Xw1t5GiBjP15ooyP+9/njj5/DywozLzYEPIn/XU6XbGqi5L72ImXpRs1pY5lWw625HTj2 u1RtILxbAqTUToIya X-Received: by 2002:a05:6402:1001:: with SMTP id c1mr8215068edu.26.1624550776304; Thu, 24 Jun 2021 09:06:16 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxno4q/K3m9BqPMkDP1H6oi4QyML09kHW15PWie27ZLhrpfBPKHQyKrcZaDXyviYFPp667eYw== X-Received: by 2002:a05:6402:1001:: with SMTP id c1mr8215048edu.26.1624550776175; Thu, 24 Jun 2021 09:06:16 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id cf3sm641548edb.39.2021.06.24.09.06.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jun 2021 09:06:15 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 5F5CC180739; Thu, 24 Jun 2021 18:06:10 +0200 (CEST) From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= To: bpf@vger.kernel.org, netdev@vger.kernel.org Cc: Martin KaFai Lau , Hangbin Liu , Jesper Dangaard Brouer , Magnus Karlsson , "Paul E . McKenney" , Jakub Kicinski , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Michael Chan Subject: [PATCH bpf-next v5 08/19] bnxt: remove rcu_read_lock() around XDP program invocation Date: Thu, 24 Jun 2021 18:05:58 +0200 Message-Id: <20210624160609.292325-9-toke@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210624160609.292325-1-toke@redhat.com> References: <20210624160609.292325-1-toke@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The bnxt driver has rcu_read_lock()/rcu_read_unlock() pairs around XDP program invocations. However, the actual lifetime of the objects referred by the XDP program invocation is longer, all the way through to the call to xdp_do_flush(), making the scope of the rcu_read_lock() too small. This turns out to be harmless because it all happens in a single NAPI poll cycle (and thus under local_bh_disable()), but it makes the rcu_read_lock() misleading. Rather than extend the scope of the rcu_read_lock(), just get rid of it entirely. With the addition of RCU annotations to the XDP_REDIRECT map types that take bh execution into account, lockdep even understands this to be safe, so there's really no reason to keep it around. Cc: Michael Chan Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c index ec9564e584e0..bee6e091a997 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c @@ -138,9 +138,7 @@ bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons, xdp_prepare_buff(&xdp, *data_ptr - offset, offset, *len, false); orig_data = xdp.data; - rcu_read_lock(); act = bpf_prog_run_xdp(xdp_prog, &xdp); - rcu_read_unlock(); tx_avail = bnxt_tx_avail(bp, txr); /* If the tx ring is not full, we must not update the rx producer yet -- 2.32.0