From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kurt Kanzenbach Subject: [PATCH 1/2] net: axienet: recheck condition after timeout in mdio_wait() Date: Tue, 30 Oct 2018 10:31:38 +0100 Message-ID: <20181030093139.10226-2-kurt@linutronix.de> References: <20181030093139.10226-1-kurt@linutronix.de> Cc: Michal Simek , Radhey Shyam Pandey , Andrew Lunn , YueHaibing , netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Kurt Kanzenbach To: Anirudha Sarangi , John Linn , "David S. Miller" Return-path: In-Reply-To: <20181030093139.10226-1-kurt@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The function could report a false positive if it gets preempted between reading the XAE_MDIO_MCR_OFFSET register and checking for the timeout. In such a case, the condition has to be rechecked to avoid false positives. Therefore, check for expected condition even after the timeout occurred. Signed-off-by: Kurt Kanzenbach --- drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c index 757a3b37ae8a..4f13125e4942 100644 --- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c @@ -21,15 +21,26 @@ int axienet_mdio_wait_until_ready(struct axienet_local *lp) { unsigned long end = jiffies + 2; - while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) & - XAE_MDIO_MCR_READY_MASK)) { + u32 val; + + while (1) { + val = axienet_ior(lp, XAE_MDIO_MCR_OFFSET); + + if (val & XAE_MDIO_MCR_READY_MASK) + return 0; + if (time_before_eq(end, jiffies)) { - WARN_ON(1); - return -ETIMEDOUT; + val = axienet_ior(lp, XAE_MDIO_MCR_OFFSET); + break; } + udelay(1); } - return 0; + if (val & XAE_MDIO_MCR_READY_MASK) + return 0; + + WARN_ON(1); + return -ETIMEDOUT; } /** -- 2.11.0