Fix the recent panics/LORs/hangs created by my kqueue commit by:

- Introducing the possibility of using locks different than mutexes
for the knlist locking. In order to do this, we add three arguments to
knlist_init() to specify the functions to use to lock, unlock and
check if the lock is owned. If these arguments are NULL, we assume
mtx_lock, mtx_unlock and mtx_owned, respectively.

- Using the vnode lock for the knlist locking, when doing kqueue operations
on a vnode. This way, we don't have to lock the vnode while holding a
mutex, in filt_vfsread.

Reviewed by:	jmg
Approved by:	re (scottl), scottl (mentor override)
Pointyhat to:	ssouhlal
Will be happy:	everyone

1 files changed, 7 insertions, 2 deletions

diff --git a/sys/sys/event.h b/sys/sys/event.h
index 82764bc..c2921c4 100644
--- a/sys/sys/event.h
+++ b/sys/sys/event.h
@@ -126,8 +126,11 @@ SLIST_HEAD(klist, knote);
 struct kqueue;
 SLIST_HEAD(kqlist, kqueue);
 struct knlist {
-	struct	mtx	*kl_lock;	/* lock to protect kll_list */
 	struct	klist	kl_list;
+	void    (*kl_lock)(void *);	/* lock function */
+	void    (*kl_unlock)(void *);
+	int    (*kl_locked)(void *);
+	void *kl_lockarg;		/* argument passed to kl_lockf() */
 };
 
 
@@ -209,7 +212,9 @@ extern void	knlist_add(struct knlist *knl, struct knote *kn, int islocked);
 extern void	knlist_remove(struct knlist *knl, struct knote *kn, int islocked);
 extern void	knlist_remove_inevent(struct knlist *knl, struct knote *kn);
 extern int	knlist_empty(struct knlist *knl);
-extern void	knlist_init(struct knlist *knl, struct mtx *mtx);
+extern void	knlist_init(struct knlist *knl, void *lock,
+    void (*kl_lock)(void *), void (*kl_unlock)(void *),
+    int (*kl_locked)(void *));
 extern void	knlist_destroy(struct knlist *knl);
 extern void	knlist_cleardel(struct knlist *knl, struct thread *td,
 	int islocked, int killkn);