Author: hselasky
Date: Sun Jan 11 12:25:10 2015
New Revision: 276972
URL: https://svnweb.freebsd.org/changeset/base/276972
Log:
MFC r276534:
The "vt_suspend_flush_timer()" function is sometimes called locked
which prevents us from doing a "callout_drain()" call. The callout in
question has a lock associated with it and we are not freeing the
callout. That means we can use the "callout_stop()" function to
atomically stop the callback iff the "callout_stop()" function is
called locked. This patch applies proper locking to "callout_stop()"
and replaces a "callout_drain()" with a "callout_stop()".
Modified:
stable/10/sys/dev/vt/vt_core.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/dev/vt/vt_core.c
==============================================================================
--- stable/10/sys/dev/vt/vt_core.c Sun Jan 11 12:21:39 2015
(r276971)
+++ stable/10/sys/dev/vt/vt_core.c Sun Jan 11 12:25:10 2015
(r276972)
@@ -114,6 +114,7 @@ const struct terminal_class vt_termclass
#define VT_LOCK(vd) mtx_lock(&(vd)->vd_lock)
#define VT_UNLOCK(vd) mtx_unlock(&(vd)->vd_lock)
+#define VT_LOCK_ASSERT(vd, what) mtx_assert(&(vd)->vd_lock, what)
#define VT_UNIT(vw) ((vw)->vw_device->vd_unit * VT_MAXWINDOWS + \
(vw)->vw_number)
@@ -282,12 +283,18 @@ vt_resume_flush_timer(struct vt_device *
static void
vt_suspend_flush_timer(struct vt_device *vd)
{
+ /*
+ * As long as this function is called locked, callout_stop()
+ * has the same effect like callout_drain() with regard to
+ * preventing the callback function from executing.
+ */
+ VT_LOCK_ASSERT(vd, MA_OWNED);
if (!(vd->vd_flags & VDF_ASYNC) ||
!atomic_cmpset_int(&vd->vd_timer_armed, 1, 0))
return;
- callout_drain(&vd->vd_timer);
+ callout_stop(&vd->vd_timer);
}
static void
@@ -2595,7 +2602,9 @@ vt_allocate(struct vt_driver *drv, void
if (vd->vd_flags & VDF_ASYNC) {
/* Stop vt_flush periodic task. */
+ VT_LOCK(vd);
vt_suspend_flush_timer(vd);
+ VT_UNLOCK(vd);
/*
* Mute current terminal until we done. vt_change_font (called
* from vt_resize) will unmute it.
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "[email protected]"
