Re: [PATCH net-next-2.6]: rtnl: make link af-specific updates atomic

[David Miller <davem@davemloft.net>]

From: Thomas Graf <tgraf@infradead.org>
Date: Mon, 22 Nov 2010 06:31:54 -0500

> As David pointed out correctly, updates to af-specific attributes
> are currently not atomic. If multiple changes are requested and
> one of them fails, previous updates may have been applied already
> leaving the link behind in a undefined state.
> 
> This patch splits the function parse_link_af() into two functions
> validate_link_af() and set_link_at(). validate_link_af() is placed
> to validate_linkmsg() check for errors as early as possible before
> any changes to the link have been made. set_link_af() is called to
> commit the changes later.
> 
> This method is not fail proof, while it is currently sufficient
> to make set_link_af() inerrable and thus 100% atomic, the
> validation function method will not be able to detect all error
> scenarios in the future, there will likely always be errors
> depending on states which are f.e. not protected by rtnl_mutex
> and thus may change between validation and setting.
> 
> Also, instead of silently ignoring unknown address families and
> config blocks for address families which did not register a set
> function the errors EAFNOSUPPORT respectively EOPNOSUPPORT are
> returned to avoid comitting 4 out of 5 update requests without
> notifying the user.
> 
> Signed-off-by: Thomas Graf <tgraf@infradead.org>

Applied, thanks Thomas.