netdev - Re: rndis gadget: Inconsistent locking

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Date:	Wed, 12 Jan 2011 14:07:12 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	David Brownell <david-b@...bell.net>,
	Michał Nazarewicz <m.nazarewicz@...sung.com>,
	Neil Jones <neiljay@...il.com>, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: rndis gadget: Inconsistent locking

Le mercredi 12 janvier 2011 à 12:28 +0000, Jarek Poplawski a écrit :
> On 2011-01-10 13:14, David Brownell wrote:
> > 
> > 
> >> I have just retested Michals patch but I have found another
> >> lockdep failure.
> >>
> >> It looks like rndis_msg_parser() can call dev_get_stats> too:
> > 
> > Can someone provide a fully working patch then?
> > Or maybe just revert the one that caused all the
> > breakage??
> > 
> > Rememeber that this driver was working fine for
> > years before netdev changes added multiple bugs
> > because (at least) they didn't update all callers.
> 
> Maybe I miss something, but if it's like Michal described something
> like this should be enough (not tested nor compiled).
> 
> Jarek P.
> ---
> 
>  drivers/usb/gadget/f_phonet.c |    6 ++++++
>  drivers/usb/gadget/u_ether.c  |    6 ++++++
>  2 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/usb/gadget/f_phonet.c b/drivers/usb/gadget/f_phonet.c
> index 3c6e1a0..bef4622 100644
> --- a/drivers/usb/gadget/f_phonet.c
> +++ b/drivers/usb/gadget/f_phonet.c
> @@ -207,6 +207,11 @@ static int pn_net_close(struct net_device *dev)
>  	return 0;
>  }
>  
> +static struct net_device_stats *pn_net_stats(struct net_device *dev)
> +{
> +	return &dev->stats;
> +}
> +
>  static void pn_tx_complete(struct usb_ep *ep, struct usb_request *req)
>  {
>  	struct f_phonet *fp = ep->driver_data;
> @@ -279,6 +284,7 @@ static int pn_net_mtu(struct net_device *dev, int new_mtu)
>  static const struct net_device_ops pn_netdev_ops = {
>  	.ndo_open	= pn_net_open,
>  	.ndo_stop	= pn_net_close,
> +	.ndo_get_stats	= pn_net_stats,
>  	.ndo_start_xmit	= pn_net_xmit,
>  	.ndo_change_mtu	= pn_net_mtu,
>  };
> diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
> index 1eda968..f21520f 100644
> --- a/drivers/usb/gadget/u_ether.c
> +++ b/drivers/usb/gadget/u_ether.c
> @@ -702,6 +702,11 @@ static int eth_stop(struct net_device *net)
>  	return 0;
>  }
>  
> +static struct net_device_stats *eth_get_stats(struct net_device *net)
> +{
> +	return &net->stats;
> +}
> +
>  /*-------------------------------------------------------------------------*/
>  
>  /* initial value, changed by "ifconfig usb0 hw ether xx:xx:xx:xx:xx:xx" */
> @@ -740,6 +745,7 @@ static struct eth_dev *the_dev;
>  static const struct net_device_ops eth_netdev_ops = {
>  	.ndo_open		= eth_open,
>  	.ndo_stop		= eth_stop,
> +	.ndo_get_stats		= eth_get_stats,
>  	.ndo_start_xmit		= eth_start_xmit,
>  	.ndo_change_mtu		= ueth_change_mtu,
>  	.ndo_set_mac_address 	= eth_mac_addr,
> --

Hmm... 

So all net devices in gen_ndis_query_resp() should have a
ndo_get_stats() or ndo_get_stats64() method, not allowed to use
spin_lock_bh() / spin_unlock_bh()

If yes, we should add big fat comments to pn_net_stats()/eth_get_stats() so that nobody
tries to revert your patch ;)



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