[PATCH] nmbclusters should be always positive

Currently, the following is allowed in FreeBSD:

root_at_rabbit1:/home/davide/udp-clt # sysctl kern.ipc.nmbclusters=2147483647
kern.ipc.nmbclusters: 2036598 -> -2147483648

The following is an attempt of fixing.
I also think nmbcluster should actually be u_int and not it, but this
is a discussion for another day, maybe.

diff --git a/sys/kern/kern_mbuf.c b/sys/kern/kern_mbuf.c
index 7ab6509..15b38a9 100644
--- a/sys/kern/kern_mbuf.c
+++ b/sys/kern/kern_mbuf.c
_at__at_ -162,7 +162,7 _at__at_ sysctl_nmbclusters(SYSCTL_HANDLER_ARGS)
        newnmbclusters = nmbclusters;
        error = sysctl_handle_int(oidp, &newnmbclusters, 0, req);
        if (error == 0 && req->newptr && newnmbclusters != nmbclusters) {
-               if (newnmbclusters > nmbclusters &&
+               if (newnmbclusters > 0 && newnmbclusters > nmbclusters &&
                    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 +
nmbjumbo16) {
                        nmbclusters = newnmbclusters;
                        nmbclusters = uma_zone_set_max(zone_clust, nmbclusters);


-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare