kern/111285: RELENG_6 em(4) watchdog timeout with IPSEC/mpsafenet

[Kris Kennaway]

The following reply was made to PR kern/111285; it has been noted by GNATS.

From: Kris Kennaway <kris at obsecurity.org>
To: Nathan Ferch <nf+fbsd at marginal.net>
Cc: freebsd-gnats-submit at FreeBSD.org
Subject: Re: kern/111285: RELENG_6 em(4) watchdog timeout with IPSEC/mpsafenet
Date: Sat, 7 Apr 2007 00:44:04 -0400

 On Thu, Apr 05, 2007 at 08:38:30PM +0000, Nathan Ferch wrote:
 
 > I am getting frequent interface lockups and watchdog timeouts with em(4) when IPSEC is loaded with mpsafenet enabled or IPSEC is compiled into the kernel.
 > 
 > I have not been able to reproduce the problem with other interfaces.
 > 
 > This problem occurs whether APIC is turned on or not.
 > >How-To-Repeat:
 > compile kernel:
 > +options                        IPSEC
 > +options                        IPSEC_ESP
 > +options                        IPSEC_DEBUG
 > 
 > OR
 > add 'debug.mpsafenet="0"' to /boot/loader.conf
 > 
 > kldload crypto
 > 
 > generate network traffic:
 > 
 > nttcp -D  -l 65535 -T 10.129.0.2 (repeat until hang/watchdog timeout)
 
 You appear to be using IPv4, so you should use FAST_IPSEC instead.
 IPSEC is deprecated and will be removed once IPv6 support is added to
 FAST_IPSEC.
 
 The issue is probably that when you set mpsafenet=0 and you generate
 extremely heavy traffic loads, the interface watchdog timer is not run
 within the timeout period (because it is competing to acquire the
 Giant lockand starved by the other traffic).
 
 Since mpsafenet=0 is only forced in legacy configurations such as the
 above, this is not really a priority to fix in itself since the real
 fix is being pursued (and is likely already available for you).
 
 Kris