From patchwork Thu Jun 24 16:05:57 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: 466719 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 74CB4C49EA6 for ; Thu, 24 Jun 2021 16:06:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 584EB613EC for ; Thu, 24 Jun 2021 16:06:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231819AbhFXQIx (ORCPT ); Thu, 24 Jun 2021 12:08:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48720 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230239AbhFXQIj (ORCPT ); Thu, 24 Jun 2021 12:08:39 -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=xn+g4Oy4TbzIlhU9jJ2+v158p0Us5HC5PaMOKTXC9pw=; b=cS2MtrCEEMS6zoSnQn23Th5xwxgnkXYqKvAr2h1hxn6vfEtxR+l//CuAHRahOaQmyjnNX6 za5eSjsYFFEHRrwx3fJ95t7Xk3Z/byT3ow11GEkux2ulRZ4Qg33CxDU7QDEaQiD07tlNIa B6Qss5C0GdUYy9LKK1Hwx4IpnZB6cDU= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-394-S9ACTl_yPFaM7FhK3AXP3w-1; Thu, 24 Jun 2021 12:06:18 -0400 X-MC-Unique: S9ACTl_yPFaM7FhK3AXP3w-1 Received: by mail-ej1-f69.google.com with SMTP id q14-20020a1709066aceb029049fa6bee56fso2158717ejs.21 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=xn+g4Oy4TbzIlhU9jJ2+v158p0Us5HC5PaMOKTXC9pw=; b=D1XEcZ2DBMW+tsMrP5xg26+m9MLsYQlEcWMVSc/OsHyRKmOSAqtzLZt1NjqtlLciAj Scl9oybgB68htMfFP/Wy0IglGPCcCg8E9dC4sUIr4jIoLtYHeL6EJTml/7w4r7X4MhKC xUyhrWg2mM3NVcfkB2389tLWCetBa9qysNSnevz33JemOh2/x8lSuLOixDRomMoD6FKE nhhWKuJ4AIE35hf4E5YBlndcjUi/KZeZyuuhZKjCmSv6Qrmg50yUppk8MVgcpZMM3ELx MtRHQ3BGijrOPmMrV9KEyB1ilLsVrewxcquDWZrohdIHC7mPKZwDV3Or3wyFoOKS1VGp Pmzw== X-Gm-Message-State: AOAM533eP7sHxYOL4mi0ypf0vITckf4sTdeDd+WxpOJOkTmpMfFOSggC UsJjoRDzupKnbyrrEFzdHIG3Fnm4+48qK3mnUR97BIItDg0MhDrv0YVOeHCZuFkTv1cEegn/Ybe UBGx9tXYApPhgOO1S X-Received: by 2002:a05:6402:4cb:: with SMTP id n11mr8118338edw.292.1624550776918; Thu, 24 Jun 2021 09:06:16 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxpnYPJAzm/4qtNBc7xfhD4QoTY11++wL13HFV4VgIRqY/z6BaZza/LEmUfZUO3YnT8+UY0ZA== X-Received: by 2002:a05:6402:4cb:: with SMTP id n11mr8118313edw.292.1624550776778; 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 x17sm2267495edr.88.2021.06.24.09.06.14 (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 53E8B180738; 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?= , Guy Tzalik , Saeed Bishara Subject: [PATCH bpf-next v5 07/19] ena: remove rcu_read_lock() around XDP program invocation Date: Thu, 24 Jun 2021 18:05:57 +0200 Message-Id: <20210624160609.292325-8-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 ena 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: Guy Tzalik Cc: Saeed Bishara Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/amazon/ena/ena_netdev.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c index 3bb0e66b2c7e..44ef6b88f715 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c @@ -382,7 +382,6 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) struct xdp_frame *xdpf; u64 *xdp_stat; - rcu_read_lock(); xdp_prog = READ_ONCE(rx_ring->xdp_bpf_prog); if (!xdp_prog) @@ -439,8 +438,6 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) ena_increase_stat(xdp_stat, 1, &rx_ring->syncp); out: - rcu_read_unlock(); - return verdict; }