svn commit: r330833 - stable/11/sys/dev/syscons

[Eitan Adler]

Author: eadler
Date: Tue Mar 13 09:29:56 2018
New Revision: 330833
URL: https://svnweb.freebsd.org/changeset/base/330833

Log:
  MFC r304161:
  
  Change all uses of 'debugger' to kdb_active and remove this variable.  This
  restores avoidance of doing dangerous things like calling wakeup() and
  callouts while in ddb.
  
  Initialization of 'debugger' was broken by removing the cndbctl() console
  method that was used mainly in this driver to initialize 'debugger' and
  switch to the console screen on entry to ddb.  The screen switch was
  restored using the cngrab() method, but cngrab() is more general so it
  should not initialize 'debugger' and never did.  'debugger' was just
  an over-engineered alias for kdb_active anyway.  It existed because
  kdb_active (when it was named ddb_active) was considered as a private
  kdb variable, and there are ordering problems initializing the variables
  atomically with the state that they represent, but an extra variable and
  method to set it increased these problems.
  
  The bug caused LORs, but WITNESS is normally misconfigured with
  WITNESS_SKIPSIN so it doesn't check the spinlocks used by wakeup() and
  callouts.

Modified:
  stable/11/sys/dev/syscons/syscons.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/syscons/syscons.c
==============================================================================
--- stable/11/sys/dev/syscons/syscons.c	Tue Mar 13 09:21:07 2018	(r330832)
+++ stable/11/sys/dev/syscons/syscons.c	Tue Mar 13 09:29:56 2018	(r330833)
@@ -172,8 +172,6 @@ SYSCTL_INT(_machdep, OID_AUTO, enable_panic_key, CTLFL
 
 #define VTY_WCHAN(sc, vty) (&SC_DEV(sc, vty))
 
-static	int		debugger;
-
 /* prototypes */
 static int sc_allocate_keyboard(sc_softc_t *sc, int unit);
 static int scvidprobe(int unit, int flags, int cons);
@@ -1815,7 +1813,7 @@ sccnupdate(scr_stat *scp)
     if (suspend_in_progress || scp->sc->font_loading_in_progress)
 	return;
 
-    if (debugger > 0 || panicstr || shutdown_in_progress) {
+    if (kdb_active || panicstr || shutdown_in_progress) {
 	sc_touch_scrn_saver();
     } else if (scp != scp->sc->cur_scp) {
 	return;
@@ -1884,7 +1882,7 @@ scrn_timer(void *arg)
 #endif /* PC98 */
 
     /* should we stop the screen saver? */
-    if (debugger > 0 || panicstr || shutdown_in_progress)
+    if (kdb_active || panicstr || shutdown_in_progress)
 	sc_touch_scrn_saver();
     if (run_scrn_saver) {
 	if (time_uptime > sc->scrn_time_stamp + scrn_blank_time)
@@ -2279,7 +2277,7 @@ stop_scrn_saver(sc_softc_t *sc, void (*saver)(sc_softc
     mark_all(sc->cur_scp);
     if (sc->delayed_next_scr)
 	sc_switch_scr(sc, sc->delayed_next_scr - 1);
-    if (debugger == 0)
+    if (!kdb_active)
 	wakeup(&scrn_blanked);
 }
 
@@ -2474,7 +2472,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next_scr)
 	    DPRINTF(5, ("error 2, requested vty isn't open!\n"));
 	    return EINVAL;
 	}
-	if ((debugger > 0) && (SC_STAT(tp)->smode.mode == VT_PROCESS)) {
+	if (kdb_active && SC_STAT(tp)->smode.mode == VT_PROCESS) {
 	    splx(s);
 	    DPRINTF(5, ("error 3, requested vty is in the VT_PROCESS mode\n"));
 	    return EINVAL;
@@ -2495,7 +2493,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next_scr)
 	 * is supposed to be locked by splhigh(), but the debugger may
 	 * be invoked at splhigh().
 	 */
-	if (debugger == 0)
+	if (!kdb_active)
 	    wakeup(VTY_WCHAN(sc,next_scr));
 	splx(s);
 	DPRINTF(5, ("switch done (new == old)\n"));
@@ -2518,7 +2516,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next_scr)
     s = spltty();
 
     /* wake up processes waiting for this vty */
-    if (debugger == 0)
+    if (!kdb_active)
 	wakeup(VTY_WCHAN(sc,next_scr));
 
     /* wait for the controlling process to acknowledge, if necessary */