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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 58AE5C4360F for ; Thu, 4 Apr 2019 09:23:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A21920693 for ; Thu, 4 Apr 2019 09:23:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369832; bh=IbPcy0E3XWWTakrYe9lPkMq0MC0r4YM+cWYRHjWsCFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2F6VpGPfyrQsIrgfcc9P9XtY+sNIHdgjLntEuOIjz1daLmhAtajTDk920fNbR4jVo q4vq1NdUT5X7Rso37xYTF1PMj+3zccBzrgJhy8FksCWaoBDEpUl2KFVnfOn/enWx9a 5gAT2qZrG2obaERryUxfQk1+fr9bGfTzGIjacWiU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387784AbfDDJO5 (ORCPT ); Thu, 4 Apr 2019 05:14:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:55790 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387786AbfDDJO4 (ORCPT ); Thu, 4 Apr 2019 05:14:56 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2BCB42054F; Thu, 4 Apr 2019 09:14:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369295; bh=IbPcy0E3XWWTakrYe9lPkMq0MC0r4YM+cWYRHjWsCFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HSDGgqEHAlTctCVO6nYOgshX1062xAhogjgWRjTA4tLDLk1XHM6hj1qwGGrd7a1WC I5HLjwBNG+7Z2NX++gjxHGqUvtMMfJ+w7JYuvKBVjHlY/rTSRh3ThbSkSA9fEWB9PB 4oW+y+a5jmdqJObZVVgbiY1pAi377LtBfpYenG4A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Heiner Kallweit , "David S. Miller" , Sasha Levin Subject: [PATCH 5.0 157/246] net: phy: consider latched link-down status in polling mode Date: Thu, 4 Apr 2019 10:47:37 +0200 Message-Id: <20190404084624.668164669@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084619.236418459@linuxfoundation.org> References: <20190404084619.236418459@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.0-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 93c0970493c71f264e6c3c7caf1ff24a9e1de786 ] The link status value latches link-down events. To get the current status we read the register twice in genphy_update_link(). There's a potential risk that we miss a link-down event in polling mode. This may cause issues if the user e.g. connects his machine to a different network. On the other hand reading the latched value may cause issues in interrupt mode. Following scenario: - After boot link goes up - phy_start() is called triggering an aneg restart, hence link goes down and link-down info is latched. - After aneg has finished link goes up and triggers an interrupt. Interrupt handler reads link status, means it reads the latched "link is down" info. But there won't be another interrupt as long as link stays up, therefore phylib will never recognize that link is up. Deal with both scenarios by reading the register twice in interrupt mode only. Signed-off-by: Heiner Kallweit Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/phy/phy-c45.c | 10 ++++++++-- drivers/net/phy/phy_device.c | 13 +++++++++---- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c index 03af927fa5ad..e39bf0428dd9 100644 --- a/drivers/net/phy/phy-c45.c +++ b/drivers/net/phy/phy-c45.c @@ -147,9 +147,15 @@ int genphy_c45_read_link(struct phy_device *phydev, u32 mmd_mask) mmd_mask &= ~BIT(devad); /* The link state is latched low so that momentary link - * drops can be detected. Do not double-read the status - * register if the link is down. + * drops can be detected. Do not double-read the status + * in polling mode to detect such short link drops. */ + if (!phy_polling_mode(phydev)) { + val = phy_read_mmd(phydev, devad, MDIO_STAT1); + if (val < 0) + return val; + } + val = phy_read_mmd(phydev, devad, MDIO_STAT1); if (val < 0) return val; diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 739434fe04fa..adf79614c2db 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1683,10 +1683,15 @@ int genphy_update_link(struct phy_device *phydev) { int status; - /* Do a fake read */ - status = phy_read(phydev, MII_BMSR); - if (status < 0) - return status; + /* The link state is latched low so that momentary link + * drops can be detected. Do not double-read the status + * in polling mode to detect such short link drops. + */ + if (!phy_polling_mode(phydev)) { + status = phy_read(phydev, MII_BMSR); + if (status < 0) + return status; + } /* Read link and autonegotiation status */ status = phy_read(phydev, MII_BMSR); -- 2.19.1