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Date: Sun, 16 Sep 2012 23:35:53 +0100
From: Ben Hutchings <bhutchings@...arflare.com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: David Miller <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>,
Maciej Żenczykowski <maze@...gle.com>
Subject: Re: [PATCH net-next 1/2] net: provide a default dev->ethtool_ops
On Sun, 2012-09-16 at 21:17 +0200, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> On Sat, 2012-09-15 at 14:40 +0100, Ben Hutchings wrote:
>
> > > strcpy(dev->name, name);
> > > dev->group = INIT_NETDEV_GROUP;
> > > + if (!dev->ethtool_ops) {
> > > + static const struct ethtool_ops default_ethtool_ops;
> > > +
> > > + dev->ethtool_ops = &default_ethtool_ops;
> > > + }
> >
> > This block has a blank line in it, so I think it needs a blank line
> > either side to make the visual grouping of code right. Alternately you
> > could pull the variable out of the block.
> >
>
> Blank line is preferred after a variable declaration in a function.
Yes but:
when the previous statement is right next to;
the start of the block {
the variable declaration is visually grouped with that;
rather than with the statement that uses it;
}
> I dont feel the need to make this variable visible outside of this
> function yet. But if you feel it, no problem.
>
> > [...]
> > > @@ -1410,8 +1409,9 @@ static int ethtool_get_module_eeprom(struct net_device *dev,
> > > modinfo.eeprom_len);
> > > }
> > >
> > > -/* The main entry point in this file. Called from net/core/dev.c */
> > > -
> > > +/* The main entry point in this file. Called from net/core/dev.c
> > > + * with RTNL held.
> > > + */
> >
> > Good point but an unrelated change.
>
> Its related, because I wanted to make clear (at least for me)
> why assuming dev->ethtool_ops was not NULL at this point was valid.
So we know it won't change under us? But that is also true of
dev->netdev_ops, which is often used with a finer-grained lock.
> > > int dev_ethtool(struct net *net, struct ifreq *ifr)
> > > {
> > > struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
> > > @@ -1419,25 +1419,15 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
> > > u32 ethcmd;
> > > int rc;
> > > u32 old_features;
> > > + const struct ethtool_ops *ops;
> > >
> > > if (!dev || !netif_device_present(dev))
> > > return -ENODEV;
> > >
> > > + ops = dev->ethtool_ops;
> > [...]
> >
> > Introducing this local variable is a useful cleanup but again should be
> > a separate change.
>
> Its a patch meant for net-next, and a cleanup. I could understand your
> point if we had to backport this to stable trees, buts its not the
> case ?
>
> I really dont care, so if you really prefer I dont cleanup ethtool.c, so
> be it.
>
> Some functions test dev->ethtool_ops is NULL, others lack this test.
> This just makes no sense to me, maybe there is something I missed.
Most of those checks are probably redundant, and I see no problem with
your removing them. It was just that you were also changing various
other references to dev->ethtool_ops to use local variables.
> Thanks
>
> [PATCH v2 net-next] net: provide a default dev->ethtool_ops
>
> Instead of forcing device drivers to provide empty ethtool_ops or tweak
> net/core/ethtool.c again, we could provide a generic ethtool_ops.
>
> This occurred to me when I wanted to add GSO support to GRE tunnels.
> ethtool -k support should be generic for all drivers.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Ben Hutchings <bhutchings@...arflare.com>
> Cc: Maciej Żenczykowski <maze@...gle.com>
Reviewed-by: Ben Hutchings <bhutchings@...arflare.com>
> ---
> net/core/dev.c | 4 ++++
> net/core/ethtool.c | 12 ------------
> 2 files changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index dcc673d..2bcb02c 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5959,6 +5959,8 @@ struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
> return queue;
> }
>
> +static const struct ethtool_ops default_ethtool_ops;
> +
> /**
> * alloc_netdev_mqs - allocate network device
> * @sizeof_priv: size of private data to allocate space for
> @@ -6046,6 +6048,8 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
>
> strcpy(dev->name, name);
> dev->group = INIT_NETDEV_GROUP;
> + if (!dev->ethtool_ops)
> + dev->ethtool_ops = &default_ethtool_ops;
> return dev;
>
> free_all:
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index cbf033d..4d64cc2 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
> @@ -1426,18 +1426,6 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
> if (copy_from_user(ðcmd, useraddr, sizeof(ethcmd)))
> return -EFAULT;
>
> - if (!dev->ethtool_ops) {
> - /* A few commands do not require any driver support,
> - * are unprivileged, and do not change anything, so we
> - * can take a shortcut to them. */
> - if (ethcmd == ETHTOOL_GDRVINFO)
> - return ethtool_get_drvinfo(dev, useraddr);
> - else if (ethcmd == ETHTOOL_GET_TS_INFO)
> - return ethtool_get_ts_info(dev, useraddr);
> - else
> - return -EOPNOTSUPP;
> - }
> -
> /* Allow some commands to be done by anyone */
> switch (ethcmd) {
> case ETHTOOL_GSET:
>
>
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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