1 files changed, 40 insertions, 4 deletions

diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
index e4906cf4ac3b..7333b3c7c1ce 100644
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -1649,11 +1649,33 @@ sc_cnterm(struct consdev *cp)
 
 static void sccnclose(sc_softc_t *sc, struct sc_cnstate *sp);
 static int sc_cngetc_locked(struct sc_cnstate *sp);
+static void sccnkbdlock(sc_softc_t *sc, struct sc_cnstate *sp);
+static void sccnkbdunlock(sc_softc_t *sc, struct sc_cnstate *sp);
 static void sccnopen(sc_softc_t *sc, struct sc_cnstate *sp, int flags);
 static void sccnscrlock(sc_softc_t *sc, struct sc_cnstate *sp);
 static void sccnscrunlock(sc_softc_t *sc, struct sc_cnstate *sp);
 
 static void
+sccnkbdlock(sc_softc_t *sc, struct sc_cnstate *sp)
+{
+    /*
+     * Locking method: hope for the best.
+     * The keyboard is supposed to be Giant locked.  We can't handle that
+     * in general.  The kdb_active case here is not safe, and we will
+     * proceed without the lock in all cases.
+     */
+    sp->kbd_locked = !kdb_active && mtx_trylock(&Giant);
+}
+
+static void
+sccnkbdunlock(sc_softc_t *sc, struct sc_cnstate *sp)
+{
+    if (sp->kbd_locked)
+	mtx_unlock(&Giant);
+    sp->kbd_locked = FALSE;
+}
+
+static void
 sccnscrlock(sc_softc_t *sc, struct sc_cnstate *sp)
 {
     SC_VIDEO_LOCK(sc);
@@ -1674,11 +1696,14 @@ sccnopen(sc_softc_t *sc, struct sc_cnstate *sp, int flags)
 
     sp->kbd_opened = FALSE;
     sp->scr_opened = FALSE;
+    sp->kbd_locked = FALSE;
 
     /* Opening the keyboard is optional. */
     if (!(flags & 1) || sc->kbd == NULL)
 	goto over_keyboard;
 
+    sccnkbdlock(sc, sp);
+
     /*
      * Make sure the keyboard is accessible even when the kbd device
      * driver is disabled.
@@ -1726,6 +1751,7 @@ sccnclose(sc_softc_t *sc, struct sc_cnstate *sp)
 
     kbdd_disable(sc->kbd);
     sp->kbd_opened = FALSE;
+    sccnkbdunlock(sc, sp);
 }
 
 /*
@@ -1751,6 +1777,7 @@ sc_cngrab(struct consdev *cp)
     if (lev >= 0 && lev < 2) {
 	sccnopen(sc, &sc->grab_state[lev], 1 | 2);
 	sccnscrunlock(sc, &sc->grab_state[lev]);
+	sccnkbdunlock(sc, &sc->grab_state[lev]);
     }
 }
 
@@ -1763,6 +1790,7 @@ sc_cnungrab(struct consdev *cp)
     sc = sc_console->sc;
     lev = atomic_load_acq_int(&sc->grab_level) - 1;
     if (lev >= 0 && lev < 2) {
+	sccnkbdlock(sc, &sc->grab_state[lev]);
 	sccnscrlock(sc, &sc->grab_state[lev]);
 	sccnclose(sc, &sc->grab_state[lev]);
     }
@@ -1825,16 +1853,20 @@ sc_cnputc(struct consdev *cd, int c)
 static int
 sc_cngetc(struct consdev *cd)
 {
+    struct sc_cnstate st;
     int c, s;
 
     /* assert(sc_console != NULL) */
+    sccnopen(sc_console->sc, &st, 1);
     s = spltty();	/* block sckbdevent and scrn_timer while we poll */
-    if (sc_console->sc->kbd == NULL) {
+    if (!st.kbd_opened) {
 	splx(s);
-	return -1;
+	sccnclose(sc_console->sc, &st);
+	return -1;	/* means no keyboard since we fudged the locking */
     }
-    c = sc_cngetc_locked(NULL);
+    c = sc_cngetc_locked(&st);
     splx(s);
+    sccnclose(sc_console->sc, &st);
     return c;
 }
 
@@ -1858,7 +1890,7 @@ sc_cngetc_locked(struct sc_cnstate *sp)
     if (fkeycp < fkey.len)
 	return fkey.str[fkeycp++];
 
-    c = scgetc(scp->sc, SCGETC_CN | SCGETC_NONBLOCK, NULL);
+    c = scgetc(scp->sc, SCGETC_CN | SCGETC_NONBLOCK, sp);
 
     switch (KEYFLAGS(c)) {
     case 0:	/* normal char */
@@ -3464,7 +3496,11 @@ next_code:
     scp = sc->cur_scp;
     /* first see if there is something in the keyboard port */
     for (;;) {
+	if (flags & SCGETC_CN)
+	    sccnscrunlock(sc, sp);
 	c = kbdd_read_char(sc->kbd, !(flags & SCGETC_NONBLOCK));
+	if (flags & SCGETC_CN)
+	    sccnscrlock(sc, sp);
 	if (c == ERRKEY) {
 	    if (!(flags & SCGETC_CN))
 		sc_bell(scp, bios_value.bell_pitch, BELL_DURATION);