[PATCH] Fix for using NFS root with if_arge

[Aleksandr Rybalko]

On Fri, 9 Mar 2012 21:53:13 -0500
Patrick Kelsey <kelsey at ieee.org> wrote:

> This patch fixes an issue I encountered using an NFS root with an
> ar71xx-based MikroTik RouterBoard 450G on -current where the kernel
> fails to contact a DHCP/BOOTP server via if_arge when it otherwise
> should be able to.  This may be the same issue that Monthadar Al
> Jaberi reported against an RSPRO on 6 March, as the signature is the
> same:
> 
> %%%
> 
> DHCP/BOOTP timeout for server 255.255.255.255
> DHCP/BOOTP timeout for server 255.255.255.255
> DHCP/BOOTP timeout for server 255.255.255.255
> .
> .
> .
> DHCP/BOOTP timeout for server 255.255.255.255
> DHCP/BOOTP timeout for server 255.255.255.255
> arge0: initialization failed: no memory for rx buffers
> DHCP/BOOTP timeout for server 255.255.255.255
> arge0: initialization failed: no memory for rx buffers
> 
> %%%
> 
> The primary issue that I found is that the DHCP/BOOTP message that
> bootpc_call() is sending never makes it onto the wire, which I
> believe is due to the following:
> 
> - Last December, a change was made to the ifioctl that bootpc_call()
> uses to adjust the netmask around the sosend().
> 
> - The new ioctl (SIOCAIFADDR) performs an if_init when invoked,
> whereas the old one (SIOCSIFNETMASK) did not.
> 
> - if_arge maintains its own sense of link state in
> sc->arge_link_status.
> 
> - On a single-phy interface, sc->arge_link_status is initialized to 0
> in arge_init_locked().
> 
> - sc->arge_link_status remains 0 until a phy state change notification
> causes arge_link_task to run, notice the link is up, and set it to 1.
> 
> - The inits caused by the ifioctls in bootpc_call are reinitializing
> the interface, but not the phy, so sc->arge_link_status goes to 0 and
> remains there.
> 
> - arge_start_locked() always sees sc->arge_link_status == 0 and
> returns without queuing anything.
> 
> 
> The attached patch changes arge_init_locked() such that in the
> single-phy case, instead of initializing sc->arge_link_status to 0,
> it runs arge_link_task() to set it according to the current phy
> state.  This change has allowed my setup to mount an NFS root
> successfully.
> 
> I think there is a secondary issue here regarding the "arge0:
> initialization failed: no memory for rx buffers".  I have not dug
> into it completely yet, but at first blush it seems that arge_stop()
> leaks mbufs from the rx ring, so after some number of arge_init()
> calls (in this case triggered by the DHCP/BOOTP message timeouts),
> all mbufs are exhausted.
> 
> -Patrick

Hi Patrick,

yeah, if_arge really have two or even three problems:
1. Different levels of allocate/free ring buffer (allocate in if_start,
but free in device_detatch), so we get memory leak when do
if_up/if_down.
2. some wrong value which sometime passed to arge_set_pll, then we try
to send some packet without run MAC clock.
3. problem that you explain

First and second fixed by http://my.ddteam.net/files/if_arge.c.patch.
Not yet commited, because not solve main problem.
We will test your patch and commit it ASAP.

Thank you!

WBW
-- 
Aleksandr Rybalko <ray at ddteam.net>