[src/trunk]: src/sys/kern kqueue_register: avoid calling fd_getfile() with fi...

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/9906edb11cd3
branches:  trunk
changeset: 771271:9906edb11cd3
user:      rmind <rmind%NetBSD.org@localhost>
date:      Thu Nov 17 22:41:55 2011 +0000

description:
kqueue_register: avoid calling fd_getfile() with filedesc_t::fd_lock held.

Fixes PR/45479 by KOGULE Ryo.

diffstat:

 sys/kern/kern_event.c |  9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diffs (46 lines):

diff -r 9e4a41dc5d1a -r 9906edb11cd3 sys/kern/kern_event.c
--- a/sys/kern/kern_event.c     Thu Nov 17 22:09:12 2011 +0000
+++ b/sys/kern/kern_event.c     Thu Nov 17 22:41:55 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_event.c,v 1.73 2011/11/17 01:19:37 christos Exp $ */
+/*     $NetBSD: kern_event.c,v 1.74 2011/11/17 22:41:55 rmind Exp $    */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.73 2011/11/17 01:19:37 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.74 2011/11/17 22:41:55 rmind Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -916,18 +916,16 @@
                return (EINVAL);
        }
 
-       mutex_enter(&fdp->fd_lock);
-
        /* search if knote already exists */
        if (kfilter->filtops->f_isfd) {
                /* monitoring a file descriptor */
                fd = kev->ident;
                if ((fp = fd_getfile(fd)) == NULL) {
-                       mutex_exit(&fdp->fd_lock);
                        rw_exit(&kqueue_filter_lock);
                        kmem_free(newkn, sizeof(*newkn));
                        return EBADF;
                }
+               mutex_enter(&fdp->fd_lock);
                ff = fdp->fd_dt->dt_ff[fd];
                if (fd <= fdp->fd_lastkqfile) {
                        SLIST_FOREACH(kn, &ff->ff_knlist, kn_link) {
@@ -941,6 +939,7 @@
                 * not monitoring a file descriptor, so
                 * lookup knotes in internal hash table
                 */
+               mutex_enter(&fdp->fd_lock);
                if (fdp->fd_knhashmask != 0) {
                        list = &fdp->fd_knhash[
                            KN_HASH((u_long)kev->ident, fdp->fd_knhashmask)];