Let filt_fileattach() run without the kernel lock

This makes it possible to attach pipe, socket and kqueue event filters
without acquiring the kernel lock. Event filters behind vn_kqfilter()
are not MP-safe yet, so vn_kqfilter() has to take KERNEL_LOCK().
dmabuf_kqfilter() can skip locking because it has no side effects.

OK anton@, mpi@

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index f33373f..f52667f 100644 (file)
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_event.c,v 1.171 2021/11/12 04:34:22 visa Exp $   */
+/*     $OpenBSD: kern_event.c,v 1.172 2021/11/13 06:04:02 visa Exp $   */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -160,7 +160,7 @@ const struct filterops proc_filtops = {
 };
 
 const struct filterops file_filtops = {
-       .f_flags        = FILTEROP_ISFD,
+       .f_flags        = FILTEROP_ISFD | FILTEROP_MPSAFE,
        .f_attach       = filt_fileattach,
        .f_detach       = NULL,
        .f_event        = NULL,

diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 5f89a6c..87182a1 100644 (file)
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vfs_vnops.c,v 1.118 2021/10/25 10:24:54 claudio Exp $ */
+/*     $OpenBSD: vfs_vnops.c,v 1.119 2021/11/13 06:04:02 visa Exp $    */
 /*     $NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $  */
 
 /*
@@ -629,7 +629,12 @@ vn_closefile(struct file *fp, struct proc *p)
 int
 vn_kqfilter(struct file *fp, struct knote *kn)
 {
-       return (VOP_KQFILTER(fp->f_data, fp->f_flag, kn));
+       int error;
+
+       KERNEL_LOCK();
+       error = VOP_KQFILTER(fp->f_data, fp->f_flag, kn);
+       KERNEL_UNLOCK();
+       return (error);
 }
 
 int