From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucas Stach Subject: Re: [PATCH v3 1/1 net] net: fec: fix kernel oops when plug/unplug cable many times Date: Mon, 06 May 2013 11:19:33 +0200 Message-ID: <1367831973.4126.16.camel@weser.hi.pengutronix.de> References: <1367456138-27172-1-git-send-email-Frank.Li@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: romieu@fr.zoreil.com, r.schwebel@pengutronix.de, davem@davemloft.net, netdev@vger.kernel.org, festevam@gmail.com, shawn.guo@linaro.org, lznuaa@gmail.com To: Frank Li Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:53135 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752502Ab3EFJUz (ORCPT ); Mon, 6 May 2013 05:20:55 -0400 In-Reply-To: <1367456138-27172-1-git-send-email-Frank.Li@freescale.com> Sender: netdev-owner@vger.kernel.org List-ID: Hi Frank, Am Donnerstag, den 02.05.2013, 08:55 +0800 schrieb Frank Li: > reproduce steps > 1. flood ping from other machine > ping -f -s 41000 IP > 2. run below script > while [ 1 ]; do ethtool -s eth0 autoneg off; > sleep 3;ethtool -s eth0 autoneg on; sleep 4; done; > > You can see oops in one hour. > > The reason is fec_restart clear BD but NAPI may use it. > The solution is disable NAPI and stop xmit when reset BD. > disable NAPI may sleep, so fec_restart can't be call in > atomic context. > > Signed-off-by: Frank Li > --- > Change from v1 to v2 > * Add netif_tx_lock(ndev) to avoid xmit runing when reset hardware > Change from v2 to v3 > * Move put real statements after function variable declarations according to David's comments > * Remove lock in adjust_link according to Lucas Stach's comments > > drivers/net/ethernet/freescale/fec.c | 42 +++++++++++++++++++++++++--------- > drivers/net/ethernet/freescale/fec.h | 3 +- > 2 files changed, 33 insertions(+), 12 deletions(-) > > diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c > index 73195f6..5a9345c 100644 > --- a/drivers/net/ethernet/freescale/fec.c > +++ b/drivers/net/ethernet/freescale/fec.c > @@ -407,6 +407,12 @@ fec_restart(struct net_device *ndev, int duplex) > u32 rcntl = OPT_FRAME_SIZE | 0x04; > u32 ecntl = 0x2; /* ETHEREN */ > > + if (netif_running(ndev)) { > + napi_disable(&fep->napi); > + netif_stop_queue(ndev); > + netif_tx_lock(ndev); > + } > + You did not address the comment from Ben Hutchings here. To make sure we are not triggering the netdev watchdog immediately when calling netif_stop_queue() we must call netif_device_detach() when entering the fec_restart and netif_device_attach() when leaving. fec_restart gets called when duplex or phy speed changes, not only in response to a link up/down change. > /* Whack a reset. We should wait for this. */ > writel(1, fep->hwp + FEC_ECNTRL); > udelay(10); > @@ -559,6 +565,12 @@ fec_restart(struct net_device *ndev, int duplex) > > /* Enable interrupts we wish to service */ > writel(FEC_DEFAULT_IMASK, fep->hwp + FEC_IMASK); > + > + if (netif_running(ndev)) { > + napi_enable(&fep->napi); > + netif_wake_queue(ndev); > + netif_tx_unlock(ndev); > + } > } > > static void > @@ -598,8 +610,20 @@ fec_timeout(struct net_device *ndev) > > ndev->stats.tx_errors++; > > - fec_restart(ndev, fep->full_duplex); > - netif_wake_queue(ndev); > + fep->timeout = 1; > + schedule_delayed_work(&fep->delay_work, msecs_to_jiffies(1)); > +} Okay, I understand you want to reuse this workqueue to do other things which might require delayed work so a delay workqueue is fine, but really use a delay of 0 here. schedule_delayed_work() internally calls down to queue_delayed_work_on() where the documentation states: "If delay is zero and dwork is idle, it will be scheduled for immediate execution.", so this is the right thing to do here. > + > +static void fec_enet_work(struct work_struct *work) > +{ > + struct fec_enet_private *fep = > + container_of(work, struct fec_enet_private, delay_work.work); > + > + if (fep->timeout) { > + fep->timeout = 0; > + fec_restart(fep->netdev, fep->full_duplex); > + netif_wake_queue(fep->netdev); > + } > } > > static void > @@ -970,16 +994,12 @@ static void fec_enet_adjust_link(struct net_device *ndev) > { > struct fec_enet_private *fep = netdev_priv(ndev); > struct phy_device *phy_dev = fep->phy_dev; > - unsigned long flags; > - > int status_change = 0; > > - spin_lock_irqsave(&fep->hw_lock, flags); > - > /* Prevent a state halted on mii error */ > if (fep->mii_timeout && phy_dev->state == PHY_HALTED) { > phy_dev->state = PHY_RESUMING; > - goto spin_unlock; > + goto exit; If we bail out here there is zero chance that we detect a link change, so drop the label and just return here. > } > > if (phy_dev->link) { > @@ -995,7 +1015,6 @@ static void fec_enet_adjust_link(struct net_device *ndev) > fep->speed = phy_dev->speed; > status_change = 1; > } > - Unnecessary whitespace change. > /* if any of the above changed restart the FEC */ > if (status_change) > fec_restart(ndev, phy_dev->duplex); > @@ -1007,11 +1026,10 @@ static void fec_enet_adjust_link(struct net_device *ndev) > } > } > > -spin_unlock: > - spin_unlock_irqrestore(&fep->hw_lock, flags); > - You are eliminating all users of the hw_lock, so please remove it altogether. Eliminate it from the fec_enet_private struct and the init in fec_enet_init(). > +exit: > if (status_change) > phy_print_status(phy_dev); > + > } > > static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum) > @@ -1882,6 +1900,7 @@ fec_probe(struct platform_device *pdev) > if (ret) > goto failed_register; > > + INIT_DELAYED_WORK(&fep->delay_work, fec_enet_work); > return 0; > > failed_register: > @@ -1918,6 +1937,7 @@ fec_drv_remove(struct platform_device *pdev) > struct resource *r; > int i; > > + cancel_delayed_work_sync(&fep->delay_work); > unregister_netdev(ndev); > fec_enet_mii_remove(fep); > del_timer_sync(&fep->time_keep); > diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h > index eb43729..a367b21 100644 > --- a/drivers/net/ethernet/freescale/fec.h > +++ b/drivers/net/ethernet/freescale/fec.h > @@ -260,7 +260,8 @@ struct fec_enet_private { > int hwts_rx_en; > int hwts_tx_en; > struct timer_list time_keep; > - > + struct delayed_work delay_work; > + int timeout; I suspect you are going to add more variables like this in the future if you are using the workqueue more extensively. This is a massive pollution of the fec_enet_private struct. Please make this a bitfield with a proper define for the timeout, so we can reuse one variable for different tasks, or even split this out into it's own struct for the delayed tasks. > }; > > void fec_ptp_init(struct net_device *ndev, struct platform_device *pdev); -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-5076 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |