From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Date: Thu, 10 Jan 2013 12:41:43 +0100 > On Thu, 2013-01-10 at 02:12 -0800, David Miller wrote: > >> >> On Wed, Jan 09, 2013 at 11:57:38PM -0800, David Miller wrote: >> >>> From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> >> >>> Date: Tue, 8 Jan 2013 16:38:51 +0100 >> >>> >> >>> > Since: >> >>> > >> >>> > commit 2c60db037034d27f8c636403355d52872da92f81 >> >>> > Author: Eric Dumazet <edumazet@xxxxxxxxxx> >> >>> > Date: Sun Sep 16 09:17:26 2012 +0000 >> >>> > >> >>> > net: provide a default dev->ethtool_ops >> >>> > >> >>> > wireless core does not correctly assign ethtool_ops. In order to fix >> >>> > the problem, move assignement of default_ethtool_ops to >> >>> > register_netdevice(). This is safe because both register_netdevice() >> >>> > and dev_ethtool() are protected by RTNL lock. >> >>> > >> >>> > Patch is besed on hint of Michał Mirosław. >> >>> > >> >>> > Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> >> >>> > Cc: stable@xxxxxxxxxxxxxxx # 3.7+ >> >>> > --- >> >>> > v1 -> v2: change order of default_ethtool_ops initialization to avoid >> >>> > the problem. Change the subject accordingly. >> >>> >> >>> I don't understand this. Why is the assignment of default_ethtool_ops >> >>> at netdev allocation time not working? Is wireless really not using >> >>> alloc_netdev*()? >> >> >> >> It does. This is done on individual cfg80211 drivers , i.e. on mac80211 >> >> or full mac drivers. After alloc_netdev*() call, some cfg80211 drivers >> >> provide they own ethtool_ops, but some do not. For them, wireless core >> >> provide generic cfg80211_ethtool_ops, which is assigned in >> >> NETDEV_REGISTER notify call: >> >> >> >> if (!dev->ethtool_ops) >> >> dev->ethtool_ops = &cfg80211_ethtool_ops; >> >> >> >> But after Eric's commit, dev->ethtool_ops is no longer NULL (on cfg80211 >> >> drivers without custom ethtool_ops), but points to &default_ethtool_ops. >> > >> > The whole idea is to remove these kinds of NULL tests against >> > dev->ethtool_ops, thus creating the invariant that given any netdev >> > one must never be able to see a non-NULL value there. >> >> Of course I meant that we should never see a NULL value in >> dev->ethtool_ops. >> >> I would suggest fixing this by making the wireless core express it's >> intentions, that it wants to use a different default ethtool ops, to >> the netdev allocation layer. >> >> You have two way to do this: >> >> 1) Add default_ethtool_ops argument to alloc_netdev*(). >> >> 2) Add a "netdev_set_default_ethtool_ops(netdev, ops)" > > Neither of these work as (I think) you think they would :-) 2) works because all netdev_set_ethtool_ops() is going to do is compare netdev->ops against &default_ethtool_ops as the test, and therefore you can replace the above cfg80211 test and assignment with a call to it. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
