From patchwork Fri Jun 10 09:45:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleksij Rempel X-Patchwork-Id: 12877258 X-Patchwork-Delegate: kuba@kernel.org 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 85997C433EF for ; Fri, 10 Jun 2022 09:45:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237820AbiFJJpi (ORCPT ); Fri, 10 Jun 2022 05:45:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244782AbiFJJpg (ORCPT ); Fri, 10 Jun 2022 05:45:36 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2FE3277F96 for ; Fri, 10 Jun 2022 02:45:33 -0700 (PDT) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nzbCi-00058b-HA; Fri, 10 Jun 2022 11:45:20 +0200 Received: from [2a0a:edc0:0:1101:1d::ac] (helo=dude04.red.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.94.2) (envelope-from ) id 1nzbCi-007YFI-8S; Fri, 10 Jun 2022 11:45:18 +0200 Received: from ore by dude04.red.stw.pengutronix.de with local (Exim 4.94.2) (envelope-from ) id 1nzbCg-005Rka-B3; Fri, 10 Jun 2022 11:45:18 +0200 From: Oleksij Rempel To: Nicolas Ferre , Claudiu Beznea , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Oleksij Rempel , kernel@pengutronix.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH net-next v1 1/1] net: macb: fix negative max_mtu size for sama5d3 Date: Fri, 10 Jun 2022 11:45:17 +0200 Message-Id: <20220610094517.1298261-1-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: netdev@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org On Microchip SAMA5D3 the JML will return null. So, after header and FCS length subtraction we will get negative max_mtu size. This issue was directly affecting DSA drivers with MTU support (for example KSZ9477). Signed-off-by: Oleksij Rempel --- drivers/net/ethernet/cadence/macb_main.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index d89098f4ede8..c7e1c9ac9809 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -4913,10 +4913,24 @@ static int macb_probe(struct platform_device *pdev) /* MTU range: 68 - 1500 or 10240 */ dev->min_mtu = GEM_MTU_MIN_SIZE; - if (bp->caps & MACB_CAPS_JUMBO) - dev->max_mtu = gem_readl(bp, JML) - ETH_HLEN - ETH_FCS_LEN; - else + if (bp->caps & MACB_CAPS_JUMBO) { + u32 val; + + if (bp->jumbo_max_len) + val = bp->jumbo_max_len; + else + val = gem_readl(bp, JML); + + if (val < ETH_DATA_LEN) { + dev_warn(&pdev->dev, "Suspicious max MTU size (%u), overwriting to %u\n", + val, ETH_DATA_LEN); + dev->max_mtu = ETH_DATA_LEN; + } else { + dev->max_mtu = val - ETH_HLEN - ETH_FCS_LEN; + } + } else { dev->max_mtu = ETH_DATA_LEN; + } if (bp->caps & MACB_CAPS_BD_RD_PREFETCH) { val = GEM_BFEXT(RXBD_RDBUFF, gem_readl(bp, DCFG10));