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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C3F3C43217 for ; Tue, 8 Nov 2022 14:07:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235114AbiKHOH3 (ORCPT ); Tue, 8 Nov 2022 09:07:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235119AbiKHOHT (ORCPT ); Tue, 8 Nov 2022 09:07:19 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 588A470573 for ; Tue, 8 Nov 2022 06:07:18 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E8F82615C4 for ; Tue, 8 Nov 2022 14:07:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03D19C433C1; Tue, 8 Nov 2022 14:07:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667916437; bh=hffPfRvaUjHfIv/dctvj4OLTluPCq59Up+EfCN5xKwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BjDwHxiFJXnH4679vVdd2M5/indche1UKHMfEyqyEh5Alb3M7K9NksBdgI6zhFTOW EpD7bLN0MgH6zSeKpjsxDmViIPNAFfKTcvYX6Umhqt7Ihw3sLMtlP0T36ylbVK4AkT 2Co8jfrEuBrhqW30UM31D+76sE0uGLdIIgOfw+Ws= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Heiko Thiery , Michael Walle , Vladimir Oltean , Florian Fainelli , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.0 020/197] net: dsa: fall back to default tagger if we cant load the one from DT Date: Tue, 8 Nov 2022 14:37:38 +0100 Message-Id: <20221108133355.693050713@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221108133354.787209461@linuxfoundation.org> References: <20221108133354.787209461@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vladimir Oltean [ Upstream commit a2c65a9d0568b6737c02b54f00b80716a53fac61 ] DSA tagging protocol drivers can be changed at runtime through sysfs and at probe time through the device tree (support for the latter was added later). When changing through sysfs, it is assumed that the module for the new tagging protocol was already loaded into the kernel (in fact this is only a concern for Ocelot/Felix switches, where we have tag_ocelot.ko and tag_ocelot_8021q.ko; for every other switch, the default and alternative protocols are compiled within the same .ko, so there is nothing for the user to load). The kernel cannot currently call request_module(), because it has no way of constructing the modalias name of the tagging protocol driver ("dsa_tag-%d", where the number is one of DSA_TAG_PROTO_*_VALUE). The device tree only contains the string name of the tagging protocol ("ocelot-8021q"), and the only mapping between the string and the DSA_TAG_PROTO_OCELOT_8021Q_VALUE is present in tag_ocelot_8021q.ko. So this is a chicken-and-egg situation and dsa_core.ko has nothing based on which it can automatically request the insertion of the module. As a consequence, if CONFIG_NET_DSA_TAG_OCELOT_8021Q is built as module, the switch will forever defer probing. The long-term solution is to make DSA call request_module() somehow, but that probably needs some refactoring. What we can do to keep operating with existing device tree blobs is to cancel the attempt to change the tagging protocol with the one specified there, and to remain operating with the default one. Depending on the situation, the default protocol might still allow some functionality (in the case of ocelot, it does), and it's better to have that than to fail to probe. Fixes: deff710703d8 ("net: dsa: Allow default tag protocol to be overridden from DT") Link: https://lore.kernel.org/lkml/20221027113248.420216-1-michael@walle.cc/ Reported-by: Heiko Thiery Reported-by: Michael Walle Signed-off-by: Vladimir Oltean Tested-by: Michael Walle Reviewed-by: Florian Fainelli Link: https://lore.kernel.org/r/20221027145439.3086017-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/dsa/dsa2.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index cac48a741f27..e537655e442b 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1407,9 +1407,9 @@ static enum dsa_tag_protocol dsa_get_tag_protocol(struct dsa_port *dp, static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master, const char *user_protocol) { + const struct dsa_device_ops *tag_ops = NULL; struct dsa_switch *ds = dp->ds; struct dsa_switch_tree *dst = ds->dst; - const struct dsa_device_ops *tag_ops; enum dsa_tag_protocol default_proto; /* Find out which protocol the switch would prefer. */ @@ -1432,10 +1432,17 @@ static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master, } tag_ops = dsa_find_tagger_by_name(user_protocol); - } else { - tag_ops = dsa_tag_driver_get(default_proto); + if (IS_ERR(tag_ops)) { + dev_warn(ds->dev, + "Failed to find a tagging driver for protocol %s, using default\n", + user_protocol); + tag_ops = NULL; + } } + if (!tag_ops) + tag_ops = dsa_tag_driver_get(default_proto); + if (IS_ERR(tag_ops)) { if (PTR_ERR(tag_ops) == -ENOPROTOOPT) return -EPROBE_DEFER; -- 2.35.1