From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sekhar Nori Subject: [PATCH net-next] drivers: net: davinci_mdio: prevent sprious timeout Date: Tue, 8 May 2018 13:56:38 +0530 Message-ID: <20180508082638.5707-1-nsekhar@ti.com> Mime-Version: 1.0 Content-Type: text/plain Cc: "David S . Miller" , , To: Grygorii Strashko Return-path: Received: from lelnx194.ext.ti.com ([198.47.27.80]:42634 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754795AbeEHI0q (ORCPT ); Tue, 8 May 2018 04:26:46 -0400 Sender: netdev-owner@vger.kernel.org List-ID: A well timed kernel preemption in the time_after() loop in wait_for_idle() can result in a spurious timeout error to be returned. Fix it by checking for status of hardware before returning timeout error. Signed-off-by: Sekhar Nori --- The issue has not been personally observed by me, but has been reported by users. Sending for next-next given the non-critical nature. There is seems to be no easy way to reproduce this. drivers/net/ethernet/ti/davinci_mdio.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/ti/davinci_mdio.c b/drivers/net/ethernet/ti/davinci_mdio.c index 3c33f4504d8e..4fbd04fd38cf 100644 --- a/drivers/net/ethernet/ti/davinci_mdio.c +++ b/drivers/net/ethernet/ti/davinci_mdio.c @@ -231,10 +231,16 @@ static inline int wait_for_idle(struct davinci_mdio_data *data) while (time_after(timeout, jiffies)) { if (__raw_readl(®s->control) & CONTROL_IDLE) - return 0; + goto out; } - dev_err(data->dev, "timed out waiting for idle\n"); - return -ETIMEDOUT; + + if (!(__raw_readl(®s->control) & CONTROL_IDLE)) { + dev_err(data->dev, "timed out waiting for idle\n"); + return -ETIMEDOUT; + } + +out: + return 0; } static int davinci_mdio_read(struct mii_bus *bus, int phy_id, int phy_reg) -- 2.16.2