netdev - Re: [RFC PATCH] e100: Fix workqueue race

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Date:	Fri, 22 Jan 2010 08:42:00 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Alan Cox <alan@...ux.intel.com>
Cc:	jesse.brandeburg@...el.com, netdev@...r.kernel.org
Subject: Re: [RFC PATCH] e100: Fix workqueue race

On 21-01-2010 17:48, Alan Cox wrote:
> (Incidentally this doesn't seem to be the only net driver that looks
> suspect here)
> 
> e100: Fix the TX workqueue race
> 
> From: Alan Cox <alan@...ux.intel.com>
> 
> Nothing stops the workqueue being left to run in parallel with close or a
> few other operations. This causes double unmaps and the like.
> 
> See kerneloops.org #1041230 for an example
> 
> Signed-off-by: Alan Cox <alan@...ux.intel.com>
> ---
> 
>  drivers/net/e100.c |   13 +++++++++++--
>  1 files changed, 11 insertions(+), 2 deletions(-)
> 
> 
> diff --git a/drivers/net/e100.c b/drivers/net/e100.c
> index 5c7a155..5e02e4f 100644
> --- a/drivers/net/e100.c
> +++ b/drivers/net/e100.c
> @@ -2232,7 +2232,7 @@ err_rx_clean_list:
>  	return err;
>  }
>  
> -static void e100_down(struct nic *nic)
> +static void e100_do_down(struct nic *nic)
>  {
>  	/* wait here for poll to complete */
>  	napi_disable(&nic->napi);
> @@ -2245,6 +2245,15 @@ static void e100_down(struct nic *nic)
>  	e100_rx_clean_list(nic);
>  }
>  
> +/* For the non TX timeout case we want to kill the tx timeout before
> +   we do this otherwise a parallel tx timeout will make a nasty mess. */
> +
> +static void e100_down(struct nic *nic)
> +{
> +	cancel_work_sync(&nic->tx_timeout_task);

Can't tx_timeout_task be triggered just between these two calls here?

Jarek P.

> +	e100_do_down(nic);
> +}
> +
>  static void e100_tx_timeout(struct net_device *netdev)
>  {
>  	struct nic *nic = netdev_priv(netdev);
> @@ -2261,7 +2270,7 @@ static void e100_tx_timeout_task(struct work_struct *work)
>  
>  	DPRINTK(TX_ERR, DEBUG, "scb.status=0x%02X\n",
>  		ioread8(&nic->csr->scb.status));
> -	e100_down(netdev_priv(netdev));
> +	e100_do_down(netdev_priv(netdev));
>  	e100_up(netdev_priv(netdev));
>  }
>  
> --
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