From patchwork Thu Jun 24 16:06:02 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: 466715 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 2B969C49EA5 for ; Thu, 24 Jun 2021 16:06:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17EAC613DC for ; Thu, 24 Jun 2021 16:06:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231941AbhFXQJG (ORCPT ); Thu, 24 Jun 2021 12:09:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60112 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231970AbhFXQI4 (ORCPT ); Thu, 24 Jun 2021 12:08:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624550797; 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=6RneWJJLq4syfEmR6mKrQCiPS0LPskxbjtJMl3vI+wY=; b=IisIGfuuhjlfFW8jpQPBz5ypPQ0VcQ9qVPZmBjKwAFsWx4+J/+Bxfvk2HlJWsmKOZT4jEe Y9UsyKbxK0oeOTNY0gsZqlOBoDsBxXjQ1SdxGSBdWkL5s4pmBJ0gfjzT4FlFdUaEBaPJTP EMoPgYCsr93hmxfJ/e+n4GS4J73JL+o= 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-434-0AAwpT_-MXq3I9UIjwgXjQ-1; Thu, 24 Jun 2021 12:06:26 -0400 X-MC-Unique: 0AAwpT_-MXq3I9UIjwgXjQ-1 Received: by mail-ed1-f69.google.com with SMTP id l9-20020a0564022549b0290394bafbfbcaso3606290edb.3 for ; Thu, 24 Jun 2021 09:06:25 -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=6RneWJJLq4syfEmR6mKrQCiPS0LPskxbjtJMl3vI+wY=; b=RCjUdDmYMlSx7WY8lRR1133rov1TpCEsdN5TpsDI/KnXbPqcLTVdm3oZqUbgUzsVSR Wcip8Lnf+wCapVw7cDfPpar/DMc5abz2fcO4w1cnk8dF0Gy0dCkU1j5ecipAZfMdgp78 GhAohPICcKzGlPOEUUO4xuXJ1VXRUbbOmwemaooBkiy7H08z2MWtrVmGVlIBo7v5uZgV jBjyE/rnYLtGm5o0PdsBjoQBePaKyAamRJG31pGXj09pNSUL5F62YaR6J2TMUHBD7+6s zDGfim7NFoXyqaInD9ihug7FG9gN+BlsCu3I9w+8efximA39eSyHa6AgXx5FV7UlSM0S G1Yg== X-Gm-Message-State: AOAM53154z5L8ShR20S4Jnf9Qis0c83B6B+tnQo6I6gSe5kVhFSD3uk8 QFDZjuLMn4+BFiE5B7JZLe1edOZE3FYag+MBCqek/2Wds+A5x+UuBVXI+T69eQQ2GaYmTHzBbXG Dacv1o1IGnBEbGbrr X-Received: by 2002:a05:6402:1c1a:: with SMTP id ck26mr8090739edb.230.1624550783310; Thu, 24 Jun 2021 09:06:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwsnVsDAn+RfC06sxjMqbpeG3bGOhaMNmAiQdvprfLfKdKQ+jGnt0sMSwNSCElGhaGOQmVlHg== X-Received: by 2002:a05:6402:1c1a:: with SMTP id ck26mr8090699edb.230.1624550782981; Thu, 24 Jun 2021 09:06:22 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id e6sm1460005ejm.35.2021.06.24.09.06.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jun 2021 09:06:21 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 82C1E18073D; Thu, 24 Jun 2021 18:06:10 +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?= , Thomas Petazzoni , Marcin Wojtas , Russell King Subject: [PATCH bpf-next v5 12/19] marvell: remove rcu_read_lock() around XDP program invocation Date: Thu, 24 Jun 2021 18:06:02 +0200 Message-Id: <20210624160609.292325-13-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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The mvneta and mvpp2 drivers have 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: Thomas Petazzoni Cc: Marcin Wojtas Cc: Russell King Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/marvell/mvneta.c | 2 -- drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 4 ---- 2 files changed, 6 deletions(-) diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index c15ce06427d0..ada4e26a5492 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c @@ -2373,7 +2373,6 @@ static int mvneta_rx_swbm(struct napi_struct *napi, /* Get number of received packets */ rx_todo = mvneta_rxq_busy_desc_num_get(pp, rxq); - rcu_read_lock(); xdp_prog = READ_ONCE(pp->xdp_prog); /* Fairness NAPI loop */ @@ -2451,7 +2450,6 @@ static int mvneta_rx_swbm(struct napi_struct *napi, xdp_buf.data_hard_start = NULL; sinfo.nr_frags = 0; } - rcu_read_unlock(); if (xdp_buf.data_hard_start) mvneta_xdp_put_buff(pp, rxq, &xdp_buf, &sinfo, -1); diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c index 9bca8c8f9f8d..c31677527a02 100644 --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c @@ -3881,8 +3881,6 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, int rx_done = 0; u32 xdp_ret = 0; - rcu_read_lock(); - xdp_prog = READ_ONCE(port->xdp_prog); /* Get number of received packets and clamp the to-do */ @@ -4028,8 +4026,6 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, mvpp2_bm_pool_put(port, pool, dma_addr, phys_addr); } - rcu_read_unlock(); - if (xdp_ret & MVPP2_XDP_REDIR) xdp_do_flush_map();