Re: [PATCH v1 net-next 1/5] ipv4: fib: Flush all fib_info in fib_table_flush() during netns dismantle.

[Ido Schimmel <idosch@nvidia.com>]

On Fri, Jun 12, 2026 at 06:32:04AM +0000, Kuniyuki Iwashima wrote:
> Even when fib_table_flush() is called with flush_all true, it does
> not flush all fib_info due to this condition:
> 
>   !(fi->fib_flags & RTNH_F_DEAD) && !fib_props[fa->fa_type].error)
> 
> This creates an implicit ordering between default_device_exit_batch()
> and fib_net_exit_batch().
> 
> fib_table_flush(flush_all=true) must be called after all devices
> are NETDEV_UNREGISTERed, which is after nexthop_flush_dev() marks
> RTNH_F_DEAD.

Nit: That's for nexthop objects. For the legacy API, the flag is set by
fib_sync_down_dev().

> 
> This would cause memory leak if the order were reversed.
> 
> fib_table_flush() does not skip non-dead error routes when flush_all
> is true:
> 
>   !flush_all &&
>   !(fi->fib_flags & RTNH_F_DEAD) && fib_props[fa->fa_type].error
> 
> Let's merge the two conditions not to skip all non-dead fib_info
> during netns dismantle.
> 
> Note that we could further apply !flush_all to the basic table
> id check and the rtmsg_fib() call in the loop.
> 
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>

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