From patchwork Thu Jun 24 16:06:00 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: 466717 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 E7537C49EA6 for ; Thu, 24 Jun 2021 16:06:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D49A1613DC for ; Thu, 24 Jun 2021 16:06:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232037AbhFXQI6 (ORCPT ); Thu, 24 Jun 2021 12:08:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24897 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231407AbhFXQIn (ORCPT ); Thu, 24 Jun 2021 12:08:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624550783; 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=8n6XcLLXm/HC8/e7TDiaIKa4D1+079NdF0CtM9PlMq8=; b=VQfWnt4zia9pxvAY3ZolyWQb1DZiqNHWkk9gscRMnuo/cU+MGikTLxu7pTuli1lLSrzh2u prv+DUPAdBuAF/2y93V4oZD9rF22Eb6UYECHQSPjik7654zBk2ICS4SlHkURBTt0wDv8m9 Lt5HtF4su8MdYpS+Bk087E03odsLcnY= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-286-fI4i4xhXM3S-j-JbOyfqug-1; Thu, 24 Jun 2021 12:06:22 -0400 X-MC-Unique: fI4i4xhXM3S-j-JbOyfqug-1 Received: by mail-ed1-f71.google.com with SMTP id v8-20020a0564023488b0290393873961f6so3593093edc.17 for ; Thu, 24 Jun 2021 09:06:21 -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=8n6XcLLXm/HC8/e7TDiaIKa4D1+079NdF0CtM9PlMq8=; b=lc60ZRk0CWttHq3gycv+TL+VRvA2feY92EJ0Q1XUA+ZbW/399SYuBFkYvcWd3Wa9c5 aywMIeA5wZajnGu+d3xMJmAEitC3GfpU+/dS7jn1Sx5AS9pFNIDTq3Vsu0OJJsE8tuKp ac+1PXpVHFPJNotp7RMenzwcSjVLsQEu+EUbwucK8mUcTt3Q7ISqolIkP4ql87Syb9/B M9/RgFc+HftE1JYKhuSi6tr+nChZJL9ZCjkus/EG4VnsInW8mKBYYJd/zzxIHZjafWov n+oNIhBS+iNCBzqlHwItAxpAHwrGpixiM1BEod8I9VF0LjOPayIMAb8Rdri4xkpTHMGv SQmA== X-Gm-Message-State: AOAM531U/Bw9nC5VDDiQSQUQ4gzUWYPwvP/tRhxcewsIS8KabxU4jGQ+ yLeR1ImJrLRctMh374f+qs8szSVkrNUewc3B/SsgePOl6Hzj5dGHAl6e/4by0leWl9RDNOJXhLY 2tcc5Ah4ALDafuWT5 X-Received: by 2002:a50:b8e6:: with SMTP id l93mr8489739ede.25.1624550780930; Thu, 24 Jun 2021 09:06:20 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx9a+Zc1daHM7E7EaR+rO9SkTP3jW41sNbM6ubu90/JqfixkamnHJK4VwcKKUiE6oKNLXWagA== X-Received: by 2002:a50:b8e6:: with SMTP id l93mr8489702ede.25.1624550780757; Thu, 24 Jun 2021 09:06:20 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id p18sm1308833edu.8.2021.06.24.09.06.14 (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 6EED918073B; 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?= , Madalin Bucur , Ioana Ciornei , Ioana Radulescu , Camelia Groza Subject: [PATCH bpf-next v5 10/19] freescale: remove rcu_read_lock() around XDP program invocation Date: Thu, 24 Jun 2021 18:06:00 +0200 Message-Id: <20210624160609.292325-11-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 dpaa and dpaa2 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: Madalin Bucur Cc: Ioana Ciornei Cc: Ioana Radulescu Reviewed-by: Camelia Groza Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 8 +------- drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 3 --- 2 files changed, 1 insertion(+), 10 deletions(-) diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c index 177c020bf34a..e6826561cf11 100644 --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c @@ -2558,13 +2558,9 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr, u32 xdp_act; int err; - rcu_read_lock(); - xdp_prog = READ_ONCE(priv->xdp_prog); - if (!xdp_prog) { - rcu_read_unlock(); + if (!xdp_prog) return XDP_PASS; - } xdp_init_buff(&xdp, DPAA_BP_RAW_SIZE - DPAA_TX_PRIV_DATA_SIZE, &dpaa_fq->xdp_rxq); @@ -2638,8 +2634,6 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr, break; } - rcu_read_unlock(); - return xdp_act; } diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c index 8433aa730c42..973352393bd4 100644 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c @@ -352,8 +352,6 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv, u32 xdp_act = XDP_PASS; int err, offset; - rcu_read_lock(); - xdp_prog = READ_ONCE(ch->xdp.prog); if (!xdp_prog) goto out; @@ -414,7 +412,6 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv, ch->xdp.res |= xdp_act; out: - rcu_read_unlock(); return xdp_act; }