[PATCH repost] net,wireless: check against default_ethtool_ops

[PATCH repost] net,wireless: check against default_ethtool_ops

[Stanislaw Gruszka]

Since:

commit 2c60db037034d27f8c636403355d52872da92f81
Author: Eric Dumazet <edumazet@google.com>
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, and avoid assigning ethtool_ops on each individual cfg80211
drivers, we check against default_ethool_ops pointer instead of NULL in
wireless core.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: stable@vger.kernel.org # 3.7+
---
This should go directly through net tree since patch include core
net specific changes.

 include/linux/netdevice.h |    2 ++
 net/core/dev.c            |    3 ++-
 net/wireless/core.c       |    2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f8eda02..c98e1c3 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -60,6 +60,8 @@ struct wireless_dev;
 #define SET_ETHTOOL_OPS(netdev,ops) \
 	( (netdev)->ethtool_ops = (ops) )
 
+extern const struct ethtool_ops default_ethtool_ops;
+
 /* hardware address assignment types */
 #define NET_ADDR_PERM		0	/* address is permanent (default) */
 #define NET_ADDR_RANDOM		1	/* address is generated randomly */
diff --git a/net/core/dev.c b/net/core/dev.c
index c0946cb..4cd2168 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6008,7 +6008,8 @@ struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
 	return queue;
 }
 
-static const struct ethtool_ops default_ethtool_ops;
+const struct ethtool_ops default_ethtool_ops;
+EXPORT_SYMBOL_GPL(default_ethtool_ops);
 
 /**
  *	alloc_netdev_mqs - allocate network device
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 14d9904..90915d4 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -866,7 +866,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		/* allow mac80211 to determine the timeout */
 		wdev->ps_timeout = -1;
 
-		if (!dev->ethtool_ops)
+		if (dev->ethtool_ops == &default_ethtool_ops)
 			dev->ethtool_ops = &cfg80211_ethtool_ops;
 
 		if ((wdev->iftype == NL80211_IFTYPE_STATION ||
-- 
1.7.1

Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Jiri Pirko]

Mon, Jan 07, 2013 at 10:55:49AM CET, sgruszka@redhat.com wrote:
>Since:
>
>commit 2c60db037034d27f8c636403355d52872da92f81
>Author: Eric Dumazet <edumazet@google.com>
>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, and avoid assigning ethtool_ops on each individual cfg80211
>drivers, we check against default_ethool_ops pointer instead of NULL in
>wireless core.
>
>Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
>Acked-by: Ben Hutchings <bhutchings@solarflare.com>
>Cc: stable@vger.kernel.org # 3.7+
>---
>This should go directly through net tree since patch include core
>net specific changes.
>
> include/linux/netdevice.h |    2 ++
> net/core/dev.c            |    3 ++-
> net/wireless/core.c       |    2 +-
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
>diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>index f8eda02..c98e1c3 100644
>--- a/include/linux/netdevice.h
>+++ b/include/linux/netdevice.h
>@@ -60,6 +60,8 @@ struct wireless_dev;
> #define SET_ETHTOOL_OPS(netdev,ops) \
> 	( (netdev)->ethtool_ops = (ops) )
> 
>+extern const struct ethtool_ops default_ethtool_ops;
>+
> /* hardware address assignment types */
> #define NET_ADDR_PERM		0	/* address is permanent (default) */
> #define NET_ADDR_RANDOM		1	/* address is generated randomly */
>diff --git a/net/core/dev.c b/net/core/dev.c
>index c0946cb..4cd2168 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -6008,7 +6008,8 @@ struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
> 	return queue;
> }
> 
>-static const struct ethtool_ops default_ethtool_ops;
>+const struct ethtool_ops default_ethtool_ops;
>+EXPORT_SYMBOL_GPL(default_ethtool_ops);

I think that default_ethtool_ops should stay static. Wouldn't it be
nicer to introduce a helper like:

bool dev_has_default_ethtool_ops(struct net_device *dev)
{
	return dev->ethtool_ops == &default_ethtool_ops;
}

> 
> /**
>  *	alloc_netdev_mqs - allocate network device
>diff --git a/net/wireless/core.c b/net/wireless/core.c
>index 14d9904..90915d4 100644
>--- a/net/wireless/core.c
>+++ b/net/wireless/core.c
>@@ -866,7 +866,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
> 		/* allow mac80211 to determine the timeout */
> 		wdev->ps_timeout = -1;
> 
>-		if (!dev->ethtool_ops)
>+		if (dev->ethtool_ops == &default_ethtool_ops)
> 			dev->ethtool_ops = &cfg80211_ethtool_ops;
> 
> 		if ((wdev->iftype == NL80211_IFTYPE_STATION ||
>-- 
>1.7.1
>
>--
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Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Stanislaw Gruszka]

On Mon, Jan 07, 2013 at 11:23:07AM +0100, Jiri Pirko wrote:
> >-static const struct ethtool_ops default_ethtool_ops;
> >+const struct ethtool_ops default_ethtool_ops;
> >+EXPORT_SYMBOL_GPL(default_ethtool_ops);
> 
> I think that default_ethtool_ops should stay static. Wouldn't it be
> nicer to introduce a helper like:
> 
> bool dev_has_default_ethtool_ops(struct net_device *dev)
> {
> 	return dev->ethtool_ops == &default_ethtool_ops;
> }

Then I still have to export this function. So with your approch, number
of exported symbols will be the same, but there will be few more lines
of code.

Stanislaw

Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Jiri Pirko]

Mon, Jan 07, 2013 at 11:44:14AM CET, sgruszka@redhat.com wrote:
>On Mon, Jan 07, 2013 at 11:23:07AM +0100, Jiri Pirko wrote:
>> >-static const struct ethtool_ops default_ethtool_ops;
>> >+const struct ethtool_ops default_ethtool_ops;
>> >+EXPORT_SYMBOL_GPL(default_ethtool_ops);
>> 
>> I think that default_ethtool_ops should stay static. Wouldn't it be
>> nicer to introduce a helper like:
>> 
>> bool dev_has_default_ethtool_ops(struct net_device *dev)
>> {
>> 	return dev->ethtool_ops == &default_ethtool_ops;
>> }
>
>Then I still have to export this function. So with your approch, number
>of exported symbols will be the same, but there will be few more lines
>of code.

I think it's always better to add few more lines in order to prevent possible
confusion which exporting default_ethtool_ops might introduce...

>
>Stanislaw

Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Stanislaw Gruszka]

On Mon, Jan 07, 2013 at 12:11:08PM +0100, Jiri Pirko wrote:
> Mon, Jan 07, 2013 at 11:44:14AM CET, sgruszka@redhat.com wrote:
> >On Mon, Jan 07, 2013 at 11:23:07AM +0100, Jiri Pirko wrote:
> >> >-static const struct ethtool_ops default_ethtool_ops;
> >> >+const struct ethtool_ops default_ethtool_ops;
> >> >+EXPORT_SYMBOL_GPL(default_ethtool_ops);
> >> 
> >> I think that default_ethtool_ops should stay static. Wouldn't it be
> >> nicer to introduce a helper like:
> >> 
> >> bool dev_has_default_ethtool_ops(struct net_device *dev)
> >> {
> >> 	return dev->ethtool_ops == &default_ethtool_ops;
> >> }
> >
> >Then I still have to export this function. So with your approch, number
> >of exported symbols will be the same, but there will be few more lines
> >of code.
> 
> I think it's always better to add few more lines in order to prevent possible
> confusion which exporting default_ethtool_ops might introduce...

What possible confusion it might cause?

Stanislaw

Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Jiri Pirko]

Mon, Jan 07, 2013 at 12:20:12PM CET, sgruszka@redhat.com wrote:
>On Mon, Jan 07, 2013 at 12:11:08PM +0100, Jiri Pirko wrote:
>> Mon, Jan 07, 2013 at 11:44:14AM CET, sgruszka@redhat.com wrote:
>> >On Mon, Jan 07, 2013 at 11:23:07AM +0100, Jiri Pirko wrote:
>> >> >-static const struct ethtool_ops default_ethtool_ops;
>> >> >+const struct ethtool_ops default_ethtool_ops;
>> >> >+EXPORT_SYMBOL_GPL(default_ethtool_ops);
>> >> 
>> >> I think that default_ethtool_ops should stay static. Wouldn't it be
>> >> nicer to introduce a helper like:
>> >> 
>> >> bool dev_has_default_ethtool_ops(struct net_device *dev)
>> >> {
>> >> 	return dev->ethtool_ops == &default_ethtool_ops;
>> >> }
>> >
>> >Then I still have to export this function. So with your approch, number
>> >of exported symbols will be the same, but there will be few more lines
>> >of code.
>> 
>> I think it's always better to add few more lines in order to prevent possible
>> confusion which exporting default_ethtool_ops might introduce...
>
>What possible confusion it might cause?

Someone would possibly like to do:

dev->netdev_ops = &default_ethtool_ops

in drivers for example...

+ I just do not think that exporting structs is the correct way in order
to do anything.

>
>Stanislaw

Re: [PATCH repost] net,wireless: check against default_ethtool_ops

[Michał Mirosław]

2013/1/7 Stanislaw Gruszka <sgruszka@redhat.com>:
> Since:
>
> commit 2c60db037034d27f8c636403355d52872da92f81
> Author: Eric Dumazet <edumazet@google.com>
> 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, and avoid assigning ethtool_ops on each individual cfg80211
> drivers, we check against default_ethool_ops pointer instead of NULL in
> wireless core.
[...]

You could instead move the assignment of default ethtool_ops to just after
call_netdevice_notifiers(NETDEV_REGISTER) in register_netdevice() or
just after call_netdevice_notifiers(NETDEV_POST_INIT) and initialize the default
wireless ethtool_ops in NETDEV_POST_INIT hook. That will avoid the export.

Either way is good because register_netdevice() is called under RTNL, so
ethtool_ops can't be called until it returns. NETDEV_POST_INIT seams more
natural to me, but it's not a strong opinion.

Best Regards,
Michał Mirosław