From e874073be0d63d3017f4d97f9ecd66838c2d9922 Mon Sep 17 00:00:00 2001 From: hselasky Date: Sun, 11 Jan 2015 12:25:10 +0000 Subject: [PATCH] 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()". git-svn-id: svn://svn.freebsd.org/base/stable/10@276972 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- sys/dev/vt/vt_core.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c index f7e3244c9..3af8b9eaf 100644 --- a/sys/dev/vt/vt_core.c +++ b/sys/dev/vt/vt_core.c @@ -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 *vd, int ms) 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 *softc) 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. -- 2.45.0