On 1/2/15 8:35 AM, Hans Petter Selasky wrote: > Author: hselasky > Date: Fri Jan 2 13:35:10 2015 > New Revision: 276534 > URL: https://svnweb.freebsd.org/changeset/base/276534 > > Log: > 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: head/sys/dev/vt/vt_core.c > ============================================================================== > --- head/sys/dev/vt/vt_core.c Fri Jan 2 13:15:36 2015 (r276533) > +++ head/sys/dev/vt/vt_core.c Fri Jan 2 13:35:10 2015 (r276534) > @@ -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) > @@ -283,12 +284,18 @@ 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);
Note that this assert is redundant. callout_stop() already asserts this for a callout initialized via callout_init_mtx(). > > 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 -- John Baldwin _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
