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, 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 55DE9C48BC2 for ; Wed, 23 Jun 2021 11:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A97261026 for ; Wed, 23 Jun 2021 11:08:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231159AbhFWLKl (ORCPT ); Wed, 23 Jun 2021 07:10:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:47402 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230403AbhFWLKU (ORCPT ); Wed, 23 Jun 2021 07:10:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624446482; 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=6wgUfE3YuyYqn3UXIkFwKI8I46axO+CjBlTP2HaYNQM=; b=hOYf9YprlHcGInqr9Qmx61xAnO/vnF1NzK7DW05B0SsJGM75s6hM2+dtjeLzKITMJacHGp MqUWTI7po0q0ZuWCOTjDHHrjBCaHJrTIuIEg4DeiiZxP2Bf3UgaR1IeKgmNDS25O1EJhS0 1BKu5zXyREkWtIHiVe0oYfvKNjXh2/A= 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-135-81JP1ZIYNeaZOI_v-6DOKQ-1; Wed, 23 Jun 2021 07:07:57 -0400 X-MC-Unique: 81JP1ZIYNeaZOI_v-6DOKQ-1 Received: by mail-ej1-f69.google.com with SMTP id c13-20020a17090603cdb029049617c6be8eso828619eja.19 for ; Wed, 23 Jun 2021 04:07:55 -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=6wgUfE3YuyYqn3UXIkFwKI8I46axO+CjBlTP2HaYNQM=; b=ceR/XBrWZ2OEQ8oGOeQRV4BY4/hMuEfrrfAvuLuTmSGlIpkq2vEPUBkqya9bY453Bv r2FX7sausS76ARp3n/dAAVulYVDHEgpwPHML+Rddzo/TH3Z/bU3Rpck/DlVGfT11sUUF J3iwBDUPOW7B0YlQMQSQa2ybXLQQC40EeenlhxiEcW3h1+nKQAWdN4hChgaj76OFsB3U B1dB5S/XmRyacmO8EXeZVayemKN/LjR2ZlUCv4P2Dpa0FRUbDTq8PDPI6tgl1Ld4hJpV TnPM/sj4CT9u5bn03nA1k9lp2htYo3gWpYZ7y1YNEzcLRd3uNb9qj8ImbO6KmkM7znKo HekA== X-Gm-Message-State: AOAM531+WKMJwZq1W9ZvvFlfTAEWJMP0B3/Kg71Hdd7QZMJeHBgycfzo 5syR6K7XyRampt7pHU37DStfN8HnAT2SDy/s56d2lohq5d7YtuRPJqkw12IXaxFj/h9+F2Nc1In eyKbpC4u6OVgfxZyg X-Received: by 2002:a17:906:244d:: with SMTP id a13mr9452851ejb.551.1624446455888; Wed, 23 Jun 2021 04:07:35 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyJuPR44sF0OT9/VupxhagYWjU/hFE+FqxoBPV+oB/0joRp0VUukfBXi80r+7q0PrJGZP+Gvw== X-Received: by 2002:a17:906:244d:: with SMTP id a13mr9452834ejb.551.1624446455697; Wed, 23 Jun 2021 04:07:35 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id n2sm13468522edi.32.2021.06.23.04.07.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jun 2021 04:07:30 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 2D0B9180738; Wed, 23 Jun 2021 13:07:28 +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?= , Michael Chan Subject: [PATCH bpf-next v4 08/19] bnxt: remove rcu_read_lock() around XDP program invocation Date: Wed, 23 Jun 2021 13:07:16 +0200 Message-Id: <20210623110727.221922-9-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 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The bnxt 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: Michael Chan Signed-off-by: Toke Høiland-Jørgensen --- drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c index ec9564e584e0..bee6e091a997 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c @@ -138,9 +138,7 @@ bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons, xdp_prepare_buff(&xdp, *data_ptr - offset, offset, *len, false); orig_data = xdp.data; - rcu_read_lock(); act = bpf_prog_run_xdp(xdp_prog, &xdp); - rcu_read_unlock(); tx_avail = bnxt_tx_avail(bp, txr); /* If the tx ring is not full, we must not update the rx producer yet -- 2.32.0