svn commit: r297742 - head/sys/netinet

[John Baldwin]

On Saturday, April 09, 2016 12:05:24 PM Bjoern A. Zeeb wrote:
> Author: bz
> Date: Sat Apr  9 12:05:23 2016
> New Revision: 297742
> URL: https://svnweb.freebsd.org/changeset/base/297742
> 
> Log:
>   Mfp: r296310,r296343
>   
>   It looks like as with the safety belt of DELAY() fastened (*) we can
>   completely tear down and free all memory for TCP (after r281599).
>   
>   (*) in theory a few ticks should be good enough to make sure the timers
>   are all really gone. Could we use a better matric here and check a
>   tcbcb count as an optimization?

In theory, no amount of DELAY() is ever enough to close a theoretical race
window.  In practice you might get lucky, but you might also panic and
trash user data.  In the rest of the tree, we tend to prefer marking items
as NOFREE instead of this approach putting a priority on stability and
reliability over memory efficiency.

For all of the zones that you removed NOFREE from, do you know why that was
added in the first place (e.g. which stale pointers to pcbs could be
referenced after free)?  Did you verify that those conditions have been
fixed?

-- 
John Baldwin