From patchwork Wed Jun 23 11:07:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 466246 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, 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 0F698C4743C for ; Wed, 23 Jun 2021 11:14:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E73AC6108E for ; Wed, 23 Jun 2021 11:14:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230397AbhFWLQV (ORCPT ); Wed, 23 Jun 2021 07:16:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39371 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230300AbhFWLQE (ORCPT ); Wed, 23 Jun 2021 07:16:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624446826; 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=3OGKlT+K3Cpr2CAOizG3FJ/dNahuGZz8NpheYYFR6ws=; b=O2zr/BJnwqEjDCfiWkYbzi2E+ox7eU/rIyC1eKXJqIcJGNrZuzvgwJD6VbtLWMESYx0Kti gQMCGnCe0BOsIjMo2SUC57fzro1Yx6D58TcoM52zx48PbDp3If0hvi4cFHQ+hZfBPAGGDm zM6YdKQc2IAvduKSyRrP3cQajp5BOrA= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-373-CYGfScniODWxXF_D6exVkA-1; Wed, 23 Jun 2021 07:13:45 -0400 X-MC-Unique: CYGfScniODWxXF_D6exVkA-1 Received: by mail-ed1-f69.google.com with SMTP id r6-20020a05640216c6b0290394ed90b605so1002961edx.20 for ; Wed, 23 Jun 2021 04:13:45 -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=3OGKlT+K3Cpr2CAOizG3FJ/dNahuGZz8NpheYYFR6ws=; b=QZwthlfNWUmyb0q5rhFuG0pNa4Z5fejynW1Yb6IDz2d5R0dLjgsUYJs3YXVXAmgkgL Jo057rSYW5KDbqQ4HvZKzmCxUakFqkwK8+wXRYZURcR3kPtyr9+4TeID0Msy1yL9fZIE 17JGs96Fp74BkIj9/wLErTLt7NHrESWOmxJYq9cWL5OXJW4uXcQS7wFAnn50f0l0F3Xj NLGxlLWqTLBIQnHHX96CdqCdOkjRgRPPOOvpf+9+QR2FDWjFn5ekCs5YL/0O+TryNNoj 4Z8sXHBS0hh4J1tKzTLHdH+tUSx6YhcJt8v+nSVChccpZMVPMSawAP70gchYpPpz2RQ3 Z7IA== X-Gm-Message-State: AOAM5319ddBxKAHT65bUZ3Fw5RM6a+3S8PEtLTCZ4ZGx203oRKMWO0BN Rvpuy/dCutIvnz+I8M7u7EGR5PjDFQeh3/dh5UaRPXu/N/BcM/Ove0PK8jI6Wdcs2Ji+JRqYngw fLSMjV5VEmuT5tBch X-Received: by 2002:a17:906:244d:: with SMTP id a13mr9481827ejb.551.1624446824262; Wed, 23 Jun 2021 04:13:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw71VQKEC/9KOOq6gTZpsMVmotp3bYZ3eOEuR03USdj7N4YBneTwSsmElAQRP2hdOY2F02acA== X-Received: by 2002:a17:906:244d:: with SMTP id a13mr9481811ejb.551.1624446824081; Wed, 23 Jun 2021 04:13:44 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id n2sm13477595edi.32.2021.06.23.04.13.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jun 2021 04:13:43 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 61ACB18073E; Wed, 23 Jun 2021 13:07:28 +0200 (CEST) From: =?utf-8?q?Toke_H=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_H=C3=B8iland-?= =?utf-8?q?J=C3=B8rgensen?= , Simon Horman , oss-drivers@netronome.com Subject: [PATCH bpf-next v4 14/19] nfp: remove rcu_read_lock() around XDP program invocation Date: Wed, 23 Jun 2021 13:07:22 +0200 Message-Id: <20210623110727.221922-15-toke@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210623110727.221922-1-toke@redhat.com> References: <20210623110727.221922-1-toke@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The nfp 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. While this is not actually an issue for the nfp driver because it doesn't support XDP_REDIRECT (and thus doesn't call xdp_do_flush()), the rcu_read_lock() is still unneeded. And 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: Simon Horman Cc: oss-drivers@netronome.com Reviewed-by: Simon Horman Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/netronome/nfp/nfp_net_common.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c index eeb30680b4dc..5dfa4799c34f 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c @@ -1819,7 +1819,6 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget) struct xdp_buff xdp; int idx; - rcu_read_lock(); xdp_prog = READ_ONCE(dp->xdp_prog); true_bufsz = xdp_prog ? PAGE_SIZE : dp->fl_bufsz; xdp_init_buff(&xdp, PAGE_SIZE - NFP_NET_RX_BUF_HEADROOM, @@ -2036,7 +2035,6 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget) if (!nfp_net_xdp_complete(tx_ring)) pkts_polled = budget; } - rcu_read_unlock(); return pkts_polled; }