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 D59C2C49EA6 for ; Thu, 24 Jun 2021 16:14:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6757613DC for ; Thu, 24 Jun 2021 16:14:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231294AbhFXQQU (ORCPT ); Thu, 24 Jun 2021 12:16:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:41224 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229881AbhFXQQP (ORCPT ); Thu, 24 Jun 2021 12:16:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624551235; 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=ZRUA/Y9lIwzUgTw5uRoa39eJ4yIyIch6xpJH66I9Qdc=; b=cS7bO3y0smmzslcOcbQjqNTn7G/V0yhkbIgWUNSzlql8EUoWkmRyWNm3VeS6MCE6NTZIDo a51RgdNMWYUixd21eTRAswB8GFYnURIckZMm61/FdBwqvMkJwSTOiDW1+mzBKZ6LMPyrS0 80IM0qpyNzmaLnxis7skY3hV1MbpDU8= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-290-bUeSWkZmNau6kWxGzIcEkg-1; Thu, 24 Jun 2021 12:13:54 -0400 X-MC-Unique: bUeSWkZmNau6kWxGzIcEkg-1 Received: by mail-ed1-f72.google.com with SMTP id ee28-20020a056402291cb0290394a9a0bfaeso3605323edb.6 for ; Thu, 24 Jun 2021 09:13:54 -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=ZRUA/Y9lIwzUgTw5uRoa39eJ4yIyIch6xpJH66I9Qdc=; b=L/Fl0+vHlf2LfisAfxgilwLDK/dlF22AZJFQCH+yIwHzkwMqbRK3fIiUnq5xaa6NCA c1IZixMyboq6kBdm3l4mrqpTvaseyGokCuwsNvMvd/FUw0H2WSLbmPnP4cMNhDdHOHaX 566qSJZGgot9jeD6y+1cpLJMbqvmaJmxDWjbhbAbqL1NzuFT9MtdxTufvt02WXGB8WrD 77+GD00z9vUtQDvuTDp31wZc0KyPyUJy8xVoOwFPlA/sm5PfdzO8DrLzagHa2nYGjzJK REBPEG+URqAa0GL2w84ohQkONxXTt9aovckITdP+igbjPJe8gU4GoiFZYsDO+AIEfyjR Nj4g== X-Gm-Message-State: AOAM530TcpLm1AbnZgp597C/dB3MEDvhUr/AEelfCvd9eD3pcawV/99k ZMAW4yoUqlPV2tBwNoOzrseX/AvgVn+1g40dE2kSVEDyy3GjzGE11ceugLADcV2tNYU0Y0uA24F Y9npwQ+eR8flF/0xY X-Received: by 2002:a17:907:6224:: with SMTP id ms36mr6015245ejc.423.1624551233262; Thu, 24 Jun 2021 09:13:53 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwT+78mtmzK35e8akO5/2A3g2OAeHLhe/rtrcwTbal1bJnAixBqQ+JAWrNGT1lmcQfMaMJFnw== X-Received: by 2002:a17:907:6224:: with SMTP id ms36mr6015201ejc.423.1624551232778; Thu, 24 Jun 2021 09:13:52 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id aq21sm1572080ejc.83.2021.06.24.09.13.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jun 2021 09:13:51 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id A1C97180740; 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?= , Ariel Elior , GR-everest-linux-l2@marvell.com Subject: [PATCH bpf-next v5 15/19] qede: remove rcu_read_lock() around XDP program invocation Date: Thu, 24 Jun 2021 18:06:05 +0200 Message-Id: <20210624160609.292325-16-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 qede 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: Ariel Elior Cc: GR-everest-linux-l2@marvell.com Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/qlogic/qede/qede_fp.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/drivers/net/ethernet/qlogic/qede/qede_fp.c b/drivers/net/ethernet/qlogic/qede/qede_fp.c index 8e150dd4f899..065e9004598e 100644 --- a/drivers/net/ethernet/qlogic/qede/qede_fp.c +++ b/drivers/net/ethernet/qlogic/qede/qede_fp.c @@ -1089,13 +1089,7 @@ static bool qede_rx_xdp(struct qede_dev *edev, xdp_prepare_buff(&xdp, page_address(bd->data), *data_offset, *len, false); - /* Queues always have a full reset currently, so for the time - * being until there's atomic program replace just mark read - * side for map helpers. - */ - rcu_read_lock(); act = bpf_prog_run_xdp(prog, &xdp); - rcu_read_unlock(); /* Recalculate, as XDP might have changed the headers */ *data_offset = xdp.data - xdp.data_hard_start; -- 2.32.0