netdev - Re: [RFC net-next 1/4] net: ipv6: Make inet6addr

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Message-ID: <20171011130845.GA11493@splinter>
Date:   Wed, 11 Oct 2017 16:08:45 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org, jiri@...lanox.com, idosch@...lanox.com,
        kjlx@...pleofstupid.com
Subject: Re: [RFC net-next 1/4] net: ipv6: Make inet6addr_validator a
 blocking notifier

On Tue, Oct 10, 2017 at 09:41:02AM -0700, David Ahern wrote:
> inet6addr_validator chain was added by commit 3ad7d2468f79f ("Ipvlan
> should return an error when an address is already in use") to allow
> address validation before changes are committed and to be able to
> fail the address change with an error back to the user. The address
> validation is not done for addresses received from router
> advertisements.
> 
> Handling RAs in softirq context is the only reason for the notifier
> chain to be atomic versus blocking. Since the only current user, ipvlan,
> of the validator chain ignores softirq context, the notifier can be made
> blocking and simply not invoked for softirq path.
> 
> The blocking option is needed by spectrum for example to validate
> resources for an adding an address to an interface.
> 
> Signed-off-by: David Ahern <dsahern@...il.com>

With the fixup posted later:

Reviewed-by: Ido Schimmel <idosch@...lanox.com>

BTW, the in_softirq() check in ipvlan_addr6_validator_event() can be
removed after this patch.