From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: Re: [PATCH v2] net: smsc911x: Quieten netif during suspend Date: Wed, 13 Sep 2017 16:28:40 -0700 Message-ID: <16f16af0-383b-9089-93c7-75494ec5031e@gmail.com> References: <1505324525-9998-1-git-send-email-geert+renesas@glider.be> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Andrew Lunn , netdev@vger.kernel.org, linux-pm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org To: Geert Uytterhoeven , "David S . Miller" , Steve Glendinning Return-path: In-Reply-To: <1505324525-9998-1-git-send-email-geert+renesas@glider.be> Content-Language: en-US Sender: linux-renesas-soc-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 09/13/2017 10:42 AM, Geert Uytterhoeven wrote: > If the network interface is kept running during suspend, the net core > may call net_device_ops.ndo_start_xmit() while the Ethernet device is > still suspended, which may lead to a system crash. > > E.g. on sh73a0/kzm9g and r8a73a4/ape6evm, the external Ethernet chip is > driven by a PM controlled clock. If the Ethernet registers are accessed > while the clock is not running, the system will crash with an imprecise > external abort. > > As this is a race condition with a small time window, it is not so easy > to trigger at will. Using pm_test may increase your chances: > > # echo 0 > /sys/module/printk/parameters/console_suspend > # echo platform > /sys/power/pm_test > # echo mem > /sys/power/state > > To fix this, make sure the network interface is quietened during > suspend. > > Signed-off-by: Geert Uytterhoeven Reviewed-by: Florian Fainelli You may want to take the opportunity to suspend the PHY device (conversely resume it) if WoL is not enabled on this device. Thanks! > --- > This is v2 of the series "[PATCH 0/2] net: Fix crashes due to activity > during suspend", which degenerated into a single patch after commit > ebc8254aeae34226 ("Revert "net: phy: Correctly process PHY_HALTED in > phy_stop_machine()"") made "[PATCH 1/2] net: phy: Freeze PHY polling before > suspending devices" no longer needed. > > v2: > - Spelling s/quit/quiet/g. > > No stacktrace is provided, as the imprecise external abort is usually > reported from an innocent looking and unrelated function like > __loop_delay(), cpu_idle_poll(), or arch_timer_read_counter_long(). > --- > drivers/net/ethernet/smsc/smsc911x.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c > index 0b6a39b003a4e188..012fb66eed8dd618 100644 > --- a/drivers/net/ethernet/smsc/smsc911x.c > +++ b/drivers/net/ethernet/smsc/smsc911x.c > @@ -2595,6 +2595,11 @@ static int smsc911x_suspend(struct device *dev) > struct net_device *ndev = dev_get_drvdata(dev); > struct smsc911x_data *pdata = netdev_priv(ndev); > > + if (netif_running(ndev)) { > + netif_stop_queue(ndev); > + netif_device_detach(ndev); > + } > + > /* enable wake on LAN, energy detection and the external PME > * signal. */ > smsc911x_reg_write(pdata, PMT_CTRL, > @@ -2628,7 +2633,15 @@ static int smsc911x_resume(struct device *dev) > while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && --to) > udelay(1000); > > - return (to == 0) ? -EIO : 0; > + if (to == 0) > + return -EIO; > + > + if (netif_running(ndev)) { > + netif_device_attach(ndev); > + netif_start_queue(ndev); > + } > + > + return 0; > } > > static const struct dev_pm_ops smsc911x_pm_ops = { > -- Florian