[src/trunk]: src/sys/dev/usb Don't touch task after calling it.

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

details:   https://anonhg.NetBSD.org/src/rev/e280644b178e
branches:  trunk
changeset: 330679:e280644b178e
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Jul 17 18:53:34 2014 +0000

description:
Don't touch task after calling it.

diffstat:

 sys/dev/usb/usb.c |  11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diffs (45 lines):

diff -r 33ceff86030e -r e280644b178e sys/dev/usb/usb.c
--- a/sys/dev/usb/usb.c Thu Jul 17 18:42:37 2014 +0000
+++ b/sys/dev/usb/usb.c Thu Jul 17 18:53:34 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: usb.c,v 1.150 2014/07/17 18:42:37 riastradh Exp $      */
+/*     $NetBSD: usb.c,v 1.151 2014/07/17 18:53:34 riastradh Exp $      */
 
 /*
  * Copyright (c) 1998, 2002, 2008, 2012 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: usb.c,v 1.150 2014/07/17 18:42:37 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: usb.c,v 1.151 2014/07/17 18:53:34 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_compat_netbsd.h"
@@ -442,6 +442,7 @@
 {
        struct usb_task *task;
        struct usb_taskq *taskq;
+       bool mpsafe;
 
        taskq = arg;
        DPRINTF(("usb_task_thread: start taskq %s\n", taskq->name));
@@ -455,14 +456,16 @@
                }
                DPRINTFN(2,("usb_task_thread: woke up task=%p\n", task));
                if (task != NULL) {
+                       mpsafe = ISSET(task->flags, USB_TASKQ_MPSAFE);
                        TAILQ_REMOVE(&taskq->tasks, task, next);
                        task->queue = USB_NUM_TASKQS;
                        mutex_exit(&taskq->lock);
 
-                       if (!(task->flags & USB_TASKQ_MPSAFE))
+                       if (!mpsafe)
                                KERNEL_LOCK(1, curlwp);
                        task->fun(task->arg);
-                       if (!(task->flags & USB_TASKQ_MPSAFE))
+                       /* Can't dereference task after this point.  */
+                       if (!mpsafe)
                                KERNEL_UNLOCK_ONE(curlwp);
 
                        mutex_enter(&taskq->lock);