Re: [PATCH net-next] sockopt: Make SO_BINDTODEVICE readable

[David Miller <davem@davemloft.net>]

From: Pavel Emelyanov <xemul@parallels.com>
Date: Fri, 19 Oct 2012 13:55:56 +0400

> The SO_BINDTODEVICE option is the only SOL_SOCKET one that can be set, but
> cannot be get via sockopt API. The only way we can find the device id a
> socket is bound to is via sock-diag interface. But the diag works only on
> hashed sockets, while the opt in question can be set for yet unhashed one.
> 
> That said, in order to know what device a socket is bound to (we do want
> to know this in checkpoint-restore project) I propose to make this option
> getsockopt-able and report the respective device index.
> 
> Another solution to the problem might be to teach the sock-diag reporting
> info on unhashed sockets. Should I go this way instead?
> 
> Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Applied.  I can't believe we didn't support this when the feature
was added.

I guess we figured that if the application made this setting, then
it knows and doesn't need to query it.