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Date: Thu, 2 May 2013 10:08:10 +0800
From: Frank Li <lznuaa@...il.com>
To: Lucas Stach <l.stach@...gutronix.de>
Cc: Frank Li <Frank.Li@...escale.com>,
Francois Romieu <romieu@...zoreil.com>,
Robert Schwebel <r.schwebel@...gutronix.de>,
David Miller <davem@...emloft.net>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Fabio Estevam <festevam@...il.com>,
Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [PATCH 1/1 v2 net] net: fec: fix kernel oops when plug/unplug
cable many times
2013/4/29 Lucas Stach <l.stach@...gutronix.de>:
> Hi Frank,
>
> Am Sonntag, den 28.04.2013, 11:08 +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 <Frank.Li@...escale.com>
>> ---
>>
>> Change from V1 to V2
>> Add netif_tx_lock(ndev) to avoid xmit runing when reset hardware
>>
>> drivers/net/ethernet/freescale/fec.c | 41 +++++++++++++++++++++++++++++-----
>> drivers/net/ethernet/freescale/fec.h | 3 +-
>> 2 files changed, 37 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c
>> index 73195f6..d140b50 100644
>> --- a/drivers/net/ethernet/freescale/fec.c
>> +++ b/drivers/net/ethernet/freescale/fec.c
>> @@ -403,6 +403,12 @@ fec_restart(struct net_device *ndev, int duplex)
>> const struct platform_device_id *id_entry =
>> platform_get_device_id(fep->pdev);
>> int i;
>> + if (netif_running(ndev)) {
>> + napi_disable(&fep->napi);
>> + netif_stop_queue(ndev);
>> + netif_tx_lock(ndev);
>> + }
>> +
>> u32 temp_mac[2];
>> u32 rcntl = OPT_FRAME_SIZE | 0x04;
>> u32 ecntl = 0x2; /* ETHEREN */
>> @@ -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));
>> +}
>
> Why are you using delayed work here? I don't see a reason why we would
> like to defer execution here. Just use schedule_work().
>
There are a silicon bug, which need delay work to workaround it.
So we can share a delay work in future.
>> +
>> +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
>> @@ -996,9 +1020,6 @@ static void fec_enet_adjust_link(struct net_device *ndev)
>> status_change = 1;
>> }
>>
>> - /* if any of the above changed restart the FEC */
>> - if (status_change)
>> - fec_restart(ndev, phy_dev->duplex);
>> } else {
>> if (fep->link) {
>> fec_stop(ndev);
>> @@ -1010,8 +1031,14 @@ static void fec_enet_adjust_link(struct net_device *ndev)
>> spin_unlock:
>> spin_unlock_irqrestore(&fep->hw_lock, flags);
>>
>> - if (status_change)
>> + if (status_change) {
>> + /* if any of the above changed restart the FEC,
>> + * fec_restart may sleep. can't call it in spin_lock
>> + */
>> + if (phy_dev->link)
>> + fec_restart(ndev, phy_dev->duplex);
>> phy_print_status(phy_dev);
>> + }
>> }
>
> Don't complicate things unnecessarily. Just put a patch in front of this
> one to remove the spinlock. As you removed it already from the RX and TX
> paths it doesn't protect anything anymore.
>
>>
>> static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
>> @@ -1882,6 +1909,7 @@ 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 +1946,7 @@ 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;
>> };
>>
>> 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 |
>
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