Adapt vfs kqfilter to the shared vnode lock used by zfs write vop. Use

vnode interlock to protect the knote fields [1]. The locking assumes
that shared vnode lock is held, thus we get exclusive access to knote
either by exclusive vnode lock protection, or by shared vnode lock +
vnode interlock.

Do not use kl_locked() method to assert either lock ownership or the
fact that curthread does not own the lock. For shared locks, ownership
is not recorded, e.g. VOP_ISLOCKED can return LK_SHARED for the shared
lock not owned by curthread, causing false positives in kqueue subsystem
assertions about knlist lock.

Remove kl_locked method from knlist lock vector, and add two separate
assertion methods kl_assert_locked and kl_assert_unlocked, that are
supposed to use proper asserts. Change knlist_init accordingly.

Add convenience function knlist_init_mtx to reduce number of arguments
for typical knlist initialization.

Submitted by:	jhb [1]
Noted by:	jhb [2]
Reviewed by:	jhb
Tested by:	rnoland

1 files changed, 4 insertions, 4 deletions

diff --git a/sys/kern/tty_pts.c b/sys/kern/tty_pts.c
index 27e481e..0b196dd 100644
--- a/sys/kern/tty_pts.c
+++ b/sys/kern/tty_pts.c
@@ -742,8 +742,8 @@ pts_alloc(int fflags, struct thread *td, struct file *fp)
 	uihold(uid);
 
 	tp = tty_alloc(&pts_class, psc);
-	knlist_init(&psc->pts_inpoll.si_note, tp->t_mtx, NULL, NULL, NULL);
-	knlist_init(&psc->pts_outpoll.si_note, tp->t_mtx, NULL, NULL, NULL);
+	knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
+	knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
 
 	/* Expose the slave device as well. */
 	tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);
@@ -782,8 +782,8 @@ pts_alloc_external(int fflags, struct thread *td, struct file *fp,
 	uihold(uid);
 
 	tp = tty_alloc(&pts_class, psc);
-	knlist_init(&psc->pts_inpoll.si_note, tp->t_mtx, NULL, NULL, NULL);
-	knlist_init(&psc->pts_outpoll.si_note, tp->t_mtx, NULL, NULL, NULL);
+	knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
+	knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
 
 	/* Expose the slave device as well. */
 	tty_makedev(tp, td->td_ucred, "%s", name);