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, 1 insertions, 1 deletions

diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index c74d09f..6c95fc6 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -648,7 +648,7 @@ bpfopen(struct cdev *dev, int flags, int fmt, struct thread *td)
 #endif
 	mtx_init(&d->bd_mtx, devtoname(dev), "bpf cdev lock", MTX_DEF);
 	callout_init(&d->bd_callout, CALLOUT_MPSAFE);
-	knlist_init(&d->bd_sel.si_note, &d->bd_mtx, NULL, NULL, NULL);
+	knlist_init_mtx(&d->bd_sel.si_note, &d->bd_mtx);
 
 	return (0);
 }