Re: rndis gadget: Inconsistent locking

Eric Dumazet
2011-01-12T13:07:12Z

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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