evdev: Extend EVIOCGRAB ioctl scope to cover kbd interface

of various keyboard drivers.
EVIOCGRAB ioctl execution on /dev/input/event# device node gains
exclusive access to this device to caller. It is used mostly for
development purposes and remote control software. See e.g.
https://reviews.freebsd.org/D30020 which is the reason of creation
of this change.
Keyboard grabbing is disabled in KDB and during panics.

MFC with:	4a0db5e292
Tested by:	corvink
Differential revision:	https://reviews.freebsd.org/D30542

sys/dev/atkbdc/atkbd.c

@@ -703,6 +703,9 @@ atkbd_read_char(keyboard_t *kbd, int wait)
 			evdev_sync(state->ks_evdev);
 		}
 	}
+
+	if (state->ks_evdev != NULL && evdev_is_grabbed(state->ks_evdev))
+		return (NOKEY);
 #endif
 
 	/* return the byte as is for the K_RAW mode */

sys/dev/evdev/evdev.c

@@ -1097,6 +1097,8 @@ evdev_release_client(struct evdev_dev *evdev, struct evdev_client *client)
 bool
 evdev_is_grabbed(struct evdev_dev *evdev)
 {
+	if (kdb_active || SCHEDULER_STOPPED())
+		return (false);
 	/*
 	 * The function is intended to be called from evdev-unrelated parts of
 	 * code like syscons-compatible parts of mouse and keyboard drivers.

sys/dev/gpio/gpiokeys.c

@@ -194,6 +194,10 @@ gpiokeys_key_event(struct gpiokeys_softc *sc, struct gpiokey *key, int pressed)
 		evdev_push_key(sc->sc_evdev, key->evcode, pressed);
 		evdev_sync(sc->sc_evdev);
 	}
+	if (evdev_is_grabbed(sc->sc_evdev)) {
+		GPIOKEYS_UNLOCK(sc);
+		return;
+	}
 #endif
 	if (key->keycode != GPIOKEY_NONE) {
 		code = key->keycode & SCAN_KEYCODE_MASK;

sys/dev/hid/hkbd.c

@@ -391,6 +391,8 @@ hkbd_put_key(struct hkbd_softc *sc, uint32_t key)
 	if (evdev_rcpt_mask & EVDEV_RCPT_HW_KBD && sc->sc_evdev != NULL)
 		evdev_push_event(sc->sc_evdev, EV_KEY,
 		    evdev_hid2key(KEY_INDEX(key)), !(key & KEY_RELEASE));
+	if (sc->sc_evdev != NULL && evdev_is_grabbed(sc->sc_evdev))
+		return;
 #endif
 
 	tail = (sc->sc_inputtail + 1) % HKBD_IN_BUF_SIZE;
@@ -541,6 +543,8 @@ hkbd_interrupt(struct hkbd_softc *sc)
 #ifdef EVDEV_SUPPORT
 	if (evdev_rcpt_mask & EVDEV_RCPT_HW_KBD && sc->sc_evdev != NULL)
 		evdev_sync(sc->sc_evdev);
+	if (sc->sc_evdev != NULL && evdev_is_grabbed(sc->sc_evdev))
+		return;
 #endif
 
 	/* wakeup keyboard system */

sys/dev/hyperv/input/hv_kbd.c

@@ -340,6 +340,8 @@ hvkbd_read_char_locked(keyboard_t *kbd, int wait)
 			evdev_sync(sc->ks_evdev);
 		}
 	}
+	if (sc->ks_evdev != NULL && evdev_is_grabbed(sc->ks_evdev))
+		return (NOKEY);
 #endif
 	++kbd->kb_count;
 	DEBUG_HVKBD(kbd, "read scan: 0x%x\n", scancode);

sys/dev/kbdmux/kbdmux.c

@@ -715,6 +715,9 @@ kbdmux_read_char(keyboard_t *kbd, int wait)
 			evdev_sync(state->ks_evdev);
 		}
 	}
+
+	if (state->ks_evdev != NULL && evdev_is_grabbed(state->ks_evdev))
+		return (NOKEY);
 #endif
 
 	/* return the byte as is for the K_RAW mode */

sys/dev/usb/input/ukbd.c

@@ -394,6 +394,8 @@ ukbd_put_key(struct ukbd_softc *sc, uint32_t key)
 	if (evdev_rcpt_mask & EVDEV_RCPT_HW_KBD && sc->sc_evdev != NULL)
 		evdev_push_event(sc->sc_evdev, EV_KEY,
 		    evdev_hid2key(KEY_INDEX(key)), !(key & KEY_RELEASE));
+	if (sc->sc_evdev != NULL && evdev_is_grabbed(sc->sc_evdev))
+		return;
 #endif
 
 	if (sc->sc_inputs < UKBD_IN_BUF_SIZE) {
@@ -562,6 +564,8 @@ ukbd_interrupt(struct ukbd_softc *sc)
 #ifdef EVDEV_SUPPORT
 	if (evdev_rcpt_mask & EVDEV_RCPT_HW_KBD && sc->sc_evdev != NULL)
 		evdev_sync(sc->sc_evdev);
+	if (sc->sc_evdev != NULL && evdev_is_grabbed(sc->sc_evdev))
+		return;
 #endif
 
 	/* wakeup keyboard system */