Add a resource limit for the total number of kqueues available to the

user.  Kqueue now saves the ucred of the allocating thread, to
correctly decrement the counter on close.

Under some specific and not real-world use scenario for kqueue, it is
possible for the kqueues to consume memory proportional to the square
of the number of the filedescriptors available to the process.  Limit
allows administrator to prevent the abuse.

This is kernel-mode side of the change, with the user-mode enabling
commit following.

Reported and tested by:	pho
Discussed with:	jmg
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

1 files changed, 3 insertions, 2 deletions

diff --git a/usr.bin/procstat/procstat_rlimit.c b/usr.bin/procstat/procstat_rlimit.c
index f3ed5fc45177..f7f67af1e0ff 100644
--- a/usr.bin/procstat/procstat_rlimit.c
+++ b/usr.bin/procstat/procstat_rlimit.c
@@ -46,7 +46,7 @@
 static struct {
 	const char *name;
 	const char *suffix;
-} rlimit_param[13] = {
+} rlimit_param[14] = {
 	{"cputime",          "sec"},
 	{"filesize",         "B  "},
 	{"datasize",         "B  "},
@@ -60,9 +60,10 @@ static struct {
 	{"vmemoryuse",       "B  "},
 	{"pseudo-terminals", "   "},
 	{"swapuse",          "B  "},
+	{"kqueues",          "   "},
 };
 
-#if RLIM_NLIMITS > 13
+#if RLIM_NLIMITS > 14
 #error "Resource limits have grown. Add new entries to rlimit_param[]."
 #endif