From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752502AbdGOBe1 (ORCPT ); Fri, 14 Jul 2017 21:34:27 -0400 Received: from fldsmtpe03.verizon.com ([140.108.26.142]:46495 "EHLO fldsmtpe03.verizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752019AbdGOB15 (ORCPT ); Fri, 14 Jul 2017 21:27:57 -0400 X-IronPort-Anti-Spam-Filtered: false From: "Levin, Alexander (Sasha Levin)" Cc: Zefir Kurtisi , "David S . Miller" , "Levin, Alexander (Sasha Levin)" X-Host: discovery.odc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH for v4.9 LTS 69/87] phy state machine: failsafe leave invalid RUNNING state Thread-Topic: [PATCH for v4.9 LTS 69/87] phy state machine: failsafe leave invalid RUNNING state Thread-Index: AQHS/Qldjwr7VSygmU+gYruJjB5Fyg== Date: Sat, 15 Jul 2017 01:26:21 +0000 Message-ID: <20170715012538.10101-69-alexander.levin@verizon.com> References: <20170715012538.10101-1-alexander.levin@verizon.com> In-Reply-To: <20170715012538.10101-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v6F1Yjgl023096 From: Zefir Kurtisi [ Upstream commit 811a919135b980bac8009d042acdccf10dc1ef5e ] While in RUNNING state, phy_state_machine() checks for link changes by comparing phydev->link before and after calling phy_read_status(). This works as long as it is guaranteed that phydev->link is never changed outside the phy_state_machine(). If in some setups this happens, it causes the state machine to miss a link loss and remain RUNNING despite phydev->link being 0. This has been observed running a dsa setup with a process continuously polling the link states over ethtool each second (SNMPD RFC-1213 agent). Disconnecting the link on a phy followed by a ETHTOOL_GSET causes dsa_slave_get_settings() / dsa_slave_get_link_ksettings() to call phy_read_status() and with that modify the link status - and with that bricking the phy state machine. This patch adds a fail-safe check while in RUNNING, which causes to move to CHANGELINK when the link is gone and we are still RUNNING. Signed-off-by: Zefir Kurtisi Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/phy/phy.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index edd30ebbf275..6e12401b5102 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -1060,6 +1060,15 @@ void phy_state_machine(struct work_struct *work) if (old_link != phydev->link) phydev->state = PHY_CHANGELINK; } + /* + * Failsafe: check that nobody set phydev->link=0 between two + * poll cycles, otherwise we won't leave RUNNING state as long + * as link remains down. + */ + if (!phydev->link && phydev->state == PHY_RUNNING) { + phydev->state = PHY_CHANGELINK; + phydev_err(phydev, "no link in PHY_RUNNING\n"); + } break; case PHY_CHANGELINK: err = phy_read_status(phydev); -- 2.11.0