[src/trunk]: src/sys/kern Test for fstrans support before trying to allocate ...

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

details:   https://anonhg.NetBSD.org/src/rev/e138854bfa11
branches:  trunk
changeset: 821961:e138854bfa11
user:      hannken <hannken%NetBSD.org@localhost>
date:      Thu Feb 23 11:23:22 2017 +0000

description:
Test for fstrans support before trying to allocate per-thread info.

PR kern/51996 (kmem_alloc called from intr context in fstrans_get_lwp_info)

diffstat:

 sys/kern/vfs_trans.c |  26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diffs (54 lines):

diff -r 4002f05ae51c -r e138854bfa11 sys/kern/vfs_trans.c
--- a/sys/kern/vfs_trans.c      Thu Feb 23 08:22:20 2017 +0000
+++ b/sys/kern/vfs_trans.c      Thu Feb 23 11:23:22 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_trans.c,v 1.36 2017/02/17 08:25:15 hannken Exp $   */
+/*     $NetBSD: vfs_trans.c,v 1.37 2017/02/23 11:23:22 hannken Exp $   */
 
 /*-
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.36 2017/02/17 08:25:15 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.37 2017/02/23 11:23:22 hannken Exp $");
 
 /*
  * File system transaction operations.
@@ -235,6 +235,16 @@
                return NULL;
 
        /*
+        * Does this file system support fstrans?
+        */
+       mutex_enter(&fstrans_mount_lock);
+       if ((mp->mnt_iflag & IMNT_HAS_TRANS) == 0) {
+               mutex_exit(&fstrans_mount_lock);
+               return NULL;
+       }
+       mutex_exit(&fstrans_mount_lock);
+
+       /*
         * Try to reuse a cleared entry or allocate a new one.
         */
        for (fli = lwp_getspecific(lwp_data_key); fli; fli = fli->fli_succ) {
@@ -274,14 +284,10 @@
         * Attach the entry to the mount.
         */
        mutex_enter(&fstrans_mount_lock);
-       if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) {
-               fli = NULL;
-       } else {
-               fmi = mp->mnt_transinfo;
-               KASSERT(fmi != NULL);
-               fli->fli_mount = mp;
-               fmi->fmi_ref_cnt += 1;
-       }
+       fmi = mp->mnt_transinfo;
+       KASSERT(fmi != NULL);
+       fli->fli_mount = mp;
+       fmi->fmi_ref_cnt += 1;
        mutex_exit(&fstrans_mount_lock);
 
        return fli;