now committed: UMA mbuf allocator use after free detection

I just commit the patch described below - if you start seeing any weird 
behavior that's networking related, please tell me - the trash allocator 
might be provoking a use after free that wasn't detected until now.

Mike "Silby" Silbersack

---------- Forwarded message ----------
Date: Wed, 15 Jun 2005 02:49:08 -0500 (CDT)
From: Mike Silbersack <silby_at_silby.com>
To: current_at_freebsd.org
Cc: Bosko Milekic <bmilekic_at_technokratis.com>
Subject: UMA mbuf allocator use after free detection


The attached patch uses the trash ctor/dtor routines from uma_dbg to help 
detect use after free conditions for mbufs, and mbuf clusters.  It doesn't seem 
to cause any unexpected problems with xl, ath, or wi, but it does cause issues 
with iwi.  That is good, because iwi has some problems that need to be 
resolved.

I'd appreciate it if people could apply the patch and see if it causes any 
panics or unexpected behavior on their systems.  If all mbuf usage is correct, 
there should be no visible effect.

This code is of course only active when you have INVARIANTS compiled in so that 
it does not slow down performance otherwise.

Thanks,

Mike "Silby" Silbersack