- Add knlist_init_rw_reader() function to kqueue(9).

Function acquired reader lock if needed.
Assert check for reader or writer lock (RA_LOCKED / RA_UNLOCKED)
- While here, add knlist_init_mtx.9 to MLINKS and fix some style(9) issues

Reviewed by:    glebius
Approved by:    ae(mentor)

MFC after:      2 weeks

share/man/man9/Makefile

@@ -773,6 +773,8 @@ MLINKS+=kqueue.9 knlist_add.9 \
 	kqueue.9 knlist_destroy.9 \
 	kqueue.9 knlist_empty.9 \
 	kqueue.9 knlist_init.9 \
+	kqueue.9 knlist_init_mtx.9 \
+	kqueue.9 knlist_init_rw_reader.9 \
 	kqueue.9 knlist_remove.9 \
 	kqueue.9 knlist_remove_inevent.9 \
 	kqueue.9 knote_fdclose.9 \

share/man/man9/kqueue.9

@@ -24,14 +24,14 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 25, 2012
+.Dd March 26, 2012
 .Dt KQUEUE 9
 .Os
 .Sh NAME
 .Nm kqueue_add_filteropts , kqueue_del_filteropts ,
 .Nm kqfd_register ,
 .Nm knote_fdclose ,
-.Nm knlist_init , knlist_init_mtx ,
+.Nm knlist_init , knlist_init_mtx , knlist_init_rw_reader ,
 .Nm knlist_add , knlist_remove , knlist_remove_inevent , knlist_empty ,
 .Nm knlist_clear , knlist_delete , knlist_destroy ,
 .Nm KNOTE_LOCKED , KNOTE_UNLOCKED
@@ -57,6 +57,8 @@
 .Ft void
 .Fn knlist_init_mtx "struct knlist *knl" "struct mtx *lock"
 .Ft void
+.Fn knlist_init_rw_reader "struct knlist *knl" "struct rwlock *lock"
+.Ft void
 .Fn knlist_add "struct knlist *knl" "struct knote *kn" "int islocked"
 .Ft void
 .Fn knlist_remove "struct knlist *knl" "struct knote *kn" "int islocked"
@@ -259,8 +261,10 @@ If used, the
 .Vt knlist
 must be initialized with either
 .Fn knlist_init
+,
+.Fn knlist_init_mtx
 or
-.Fn knlist_init_mtx .
+.Fn knlist_init_rw_reader .
 The
 .Vt knlist
 structure may be embedded into the object structure.
@@ -305,6 +309,19 @@ style
 lock.
 .Pp
 The function
+.Fn knlist_init_rw_reader
+may be used to initialize a
+.Vt knlist
+when
+.Fa lock
+is a
+.Xr rwlock 9
+read lock.
+Lock is acquired via
+.Fn rw_rlock
+function.
+.Pp
+The function
 .Fn knlist_empty
 returns true when there are no
 .Vt knotes

sys/kern/kern_event.c

@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/rwlock.h>
 #include <sys/proc.h>
 #include <sys/malloc.h>
 #include <sys/unistd.h>
@@ -1869,6 +1870,7 @@ knlist_remove_inevent(struct knlist *knl, struct knote *kn)
 int
 knlist_empty(struct knlist *knl)
 {
+
 	KNL_ASSERT_LOCKED(knl);
 	return SLIST_EMPTY(&knl->kl_list);
 }
@@ -1882,27 +1884,59 @@ static void knlist_mtx_unlock(void *arg);
 static void
 knlist_mtx_lock(void *arg)
 {
+
 	mtx_lock((struct mtx *)arg);
 }
 
 static void
 knlist_mtx_unlock(void *arg)
 {
+
 	mtx_unlock((struct mtx *)arg);
 }
 
 static void
 knlist_mtx_assert_locked(void *arg)
 {
+
 	mtx_assert((struct mtx *)arg, MA_OWNED);
 }
 
 static void
 knlist_mtx_assert_unlocked(void *arg)
 {
+
 	mtx_assert((struct mtx *)arg, MA_NOTOWNED);
 }
 
+static void
+knlist_rw_rlock(void *arg)
+{
+
+	rw_rlock((struct rwlock *)arg);
+}
+
+static void
+knlist_rw_runlock(void *arg)
+{
+
+	rw_runlock((struct rwlock *)arg);
+}
+
+static void
+knlist_rw_assert_locked(void *arg)
+{
+
+	rw_assert((struct rwlock *)arg, RA_LOCKED);
+}
+
+static void
+knlist_rw_assert_unlocked(void *arg)
+{
+
+	rw_assert((struct rwlock *)arg, RA_UNLOCKED);
+}
+
 void
 knlist_init(struct knlist *knl, void *lock, void (*kl_lock)(void *),
     void (*kl_unlock)(void *),
@@ -1941,6 +1975,14 @@ knlist_init_mtx(struct knlist *knl, struct mtx *lock)
 	knlist_init(knl, lock, NULL, NULL, NULL, NULL);
 }
 
+void
+knlist_init_rw_reader(struct knlist *knl, struct rwlock *lock)
+{
+
+	knlist_init(knl, lock, knlist_rw_rlock, knlist_rw_runlock,
+	    knlist_rw_assert_locked, knlist_rw_assert_unlocked);
+}
+
 void
 knlist_destroy(struct knlist *knl)
 {

sys/sys/event.h

@@ -234,6 +234,7 @@ struct thread;
 struct proc;
 struct knlist;
 struct mtx;
+struct rwlock;
 
 extern void	knote(struct knlist *list, long hint, int lockflags);
 extern void	knote_fork(struct knlist *list, int pid);
@@ -245,6 +246,7 @@ extern void	knlist_init(struct knlist *knl, void *lock,
     void (*kl_lock)(void *), void (*kl_unlock)(void *),
     void (*kl_assert_locked)(void *), void (*kl_assert_unlocked)(void *));
 extern void	knlist_init_mtx(struct knlist *knl, struct mtx *lock);
+extern void	knlist_init_rw_reader(struct knlist *knl, struct rwlock *lock);
 extern void	knlist_destroy(struct knlist *knl);
 extern void	knlist_cleardel(struct knlist *knl, struct thread *td,
 	int islocked, int killkn);