kbd: replace vestigial spl calls with Giant assertions

The keyboard driver was initially protected via spl* interrupt priority
calls but (as part of a comprehensive effort) migrated to use the Giant
lock (mutex).

The spl calls left behind became NOPs but they can be confusing as they
have no bearing on the actual mutual exclusion that is now present.

Remove them from kbd and add assertions that Giant is held.  markj notes
that there is conflation between the "bus topo" lock (which is Giant
under the hood) and Giant.  The assertions could either be addressed as
a small item along with bus topology locking work or they'll be removed
if kbd is decoupled from Giant.

PR:		206680
Reviewed by:	markj
MFC after:	3 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D34645

1 files changed, 12 insertions, 55 deletions

diff --git a/sys/dev/kbd/kbd.c b/sys/dev/kbd/kbd.c
index 70c0ef15a56e..deb7672de7fa 100644
--- a/sys/dev/kbd/kbd.c
+++ b/sys/dev/kbd/kbd.c
@@ -35,7 +35,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
+#include <sys/lock.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
 #include <sys/conf.h>
 #include <sys/fcntl.h>
 #include <sys/poll.h>
@@ -97,13 +99,11 @@ kbd_realloc_array(void)
 {
 	keyboard_t **new_kbd;
 	int newsize;
-	int s;
 
-	s = spltty();
+	GIANT_REQUIRED;
 	newsize = rounddown(keyboards + ARRAY_DELTA, ARRAY_DELTA);
 	new_kbd = malloc(sizeof(*new_kbd)*newsize, M_DEVBUF, M_NOWAIT|M_ZERO);
 	if (new_kbd == NULL) {
-		splx(s);
 		return (ENOMEM);
 	}
 	bcopy(keyboard, new_kbd, sizeof(*keyboard)*keyboards);
@@ -111,7 +111,6 @@ kbd_realloc_array(void)
 		free(keyboard, M_DEVBUF);
 	keyboard = new_kbd;
 	keyboards = newsize;
-	splx(s);
 
 	if (bootverbose)
 		printf("kbd: new array size %d\n", keyboards);
@@ -245,30 +244,26 @@ int
 kbd_unregister(keyboard_t *kbd)
 {
 	int error;
-	int s;
 
+	GIANT_REQUIRED;
 	if ((kbd->kb_index < 0) || (kbd->kb_index >= keyboards))
 		return (ENOENT);
 	if (keyboard[kbd->kb_index] != kbd)
 		return (ENOENT);
 
-	s = spltty();
 	if (KBD_IS_BUSY(kbd)) {
 		error = (*kbd->kb_callback.kc_func)(kbd, KBDIO_UNLOADING,
 		    kbd->kb_callback.kc_arg);
 		if (error) {
-			splx(s);
 			return (error);
 		}
 		if (KBD_IS_BUSY(kbd)) {
-			splx(s);
 			return (EBUSY);
 		}
 	}
 	KBD_INVALID(kbd);
 	keyboard[kbd->kb_index] = NULL;
 
-	splx(s);
 	return (0);
 }
 
@@ -333,16 +328,14 @@ kbd_allocate(char *driver, int unit, void *id, kbd_callback_func_t *func,
 	     void *arg)
 {
 	int index;
-	int s;
 
+	GIANT_REQUIRED;
 	if (func == NULL)
 		return (-1);
 
-	s = spltty();
 	index = kbd_find_keyboard(driver, unit);
 	if (index >= 0) {
 		if (KBD_IS_BUSY(keyboard[index])) {
-			splx(s);
 			return (-1);
 		}
 		keyboard[index]->kb_token = id;
@@ -351,7 +344,6 @@ kbd_allocate(char *driver, int unit, void *id, kbd_callback_func_t *func,
 		keyboard[index]->kb_callback.kc_arg = arg;
 		kbdd_clear_state(keyboard[index]);
 	}
-	splx(s);
 	return (index);
 }
 
@@ -359,9 +351,8 @@ int
 kbd_release(keyboard_t *kbd, void *id)
 {
 	int error;
-	int s;
 
-	s = spltty();
+	GIANT_REQUIRED;
 	if (!KBD_IS_VALID(kbd) || !KBD_IS_BUSY(kbd)) {
 		error = EINVAL;
 	} else if (kbd->kb_token != id) {
@@ -374,7 +365,6 @@ kbd_release(keyboard_t *kbd, void *id)
 		kbdd_clear_state(kbd);
 		error = 0;
 	}
-	splx(s);
 	return (error);
 }
 
@@ -383,9 +373,8 @@ kbd_change_callback(keyboard_t *kbd, void *id, kbd_callback_func_t *func,
 		    void *arg)
 {
 	int error;
-	int s;
 
-	s = spltty();
+	GIANT_REQUIRED;
 	if (!KBD_IS_VALID(kbd) || !KBD_IS_BUSY(kbd)) {
 		error = EINVAL;
 	} else if (kbd->kb_token != id) {
@@ -397,7 +386,6 @@ kbd_change_callback(keyboard_t *kbd, void *id, kbd_callback_func_t *func,
 		kbd->kb_callback.kc_arg = arg;
 		error = 0;
 	}
-	splx(s);
 	return (error);
 }
 
@@ -542,20 +530,17 @@ genkbdopen(struct cdev *dev, int mode, int flag, struct thread *td)
 {
 	keyboard_t *kbd;
 	genkbd_softc_t *sc;
-	int s;
 	int i;
 
-	s = spltty();
+	GIANT_REQUIRED;
 	sc = dev->si_drv1;
 	kbd = kbd_get_keyboard(KBD_INDEX(dev));
 	if ((sc == NULL) || (kbd == NULL) || !KBD_IS_VALID(kbd)) {
-		splx(s);
 		return (ENXIO);
 	}
 	i = kbd_allocate(kbd->kb_name, kbd->kb_unit, sc,
 	    genkbd_event, (void *)sc);
 	if (i < 0) {
-		splx(s);
 		return (EBUSY);
 	}
 	/* assert(i == kbd->kb_index) */
@@ -567,7 +552,6 @@ genkbdopen(struct cdev *dev, int mode, int flag, struct thread *td)
 	 */
 
 	sc->gkb_q_length = 0;
-	splx(s);
 
 	return (0);
 }
@@ -577,13 +561,12 @@ genkbdclose(struct cdev *dev, int mode, int flag, struct thread *td)
 {
 	keyboard_t *kbd;
 	genkbd_softc_t *sc;
-	int s;
 
+	GIANT_REQUIRED;
 	/*
 	 * NOTE: the device may have already become invalid.
 	 * kbd == NULL || !KBD_IS_VALID(kbd)
 	 */
-	s = spltty();
 	sc = dev->si_drv1;
 	kbd = kbd_get_keyboard(KBD_INDEX(dev));
 	if ((sc == NULL) || (kbd == NULL) || !KBD_IS_VALID(kbd)) {
@@ -591,7 +574,6 @@ genkbdclose(struct cdev *dev, int mode, int flag, struct thread *td)
 	} else {
 		kbd_release(kbd, (void *)sc);
 	}
-	splx(s);
 	return (0);
 }
 
@@ -603,35 +585,29 @@ genkbdread(struct cdev *dev, struct uio *uio, int flag)
 	u_char buffer[KB_BUFSIZE];
 	int len;
 	int error;
-	int s;
 
+	GIANT_REQUIRED;
 	/* wait for input */
-	s = spltty();
 	sc = dev->si_drv1;
 	kbd = kbd_get_keyboard(KBD_INDEX(dev));
 	if ((sc == NULL) || (kbd == NULL) || !KBD_IS_VALID(kbd)) {
-		splx(s);
 		return (ENXIO);
 	}
 	while (sc->gkb_q_length == 0) {
 		if (flag & O_NONBLOCK) {
-			splx(s);
 			return (EWOULDBLOCK);
 		}
 		sc->gkb_flags |= KB_ASLEEP;
 		error = tsleep(sc, PZERO | PCATCH, "kbdrea", 0);
 		kbd = kbd_get_keyboard(KBD_INDEX(dev));
 		if ((kbd == NULL) || !KBD_IS_VALID(kbd)) {
-			splx(s);
 			return (ENXIO);	/* our keyboard has gone... */
 		}
 		if (error) {
 			sc->gkb_flags &= ~KB_ASLEEP;
-			splx(s);
 			return (error);
 		}
 	}
-	splx(s);
 
 	/* copy as much input as possible */
 	error = 0;
@@ -680,10 +656,9 @@ genkbdpoll(struct cdev *dev, int events, struct thread *td)
 	keyboard_t *kbd;
 	genkbd_softc_t *sc;
 	int revents;
-	int s;
 
+	GIANT_REQUIRED;
 	revents = 0;
-	s = spltty();
 	sc = dev->si_drv1;
 	kbd = kbd_get_keyboard(KBD_INDEX(dev));
 	if ((sc == NULL) || (kbd == NULL) || !KBD_IS_VALID(kbd)) {
@@ -694,7 +669,6 @@ genkbdpoll(struct cdev *dev, int events, struct thread *td)
 		else
 			selrecord(td, &sc->gkb_rsel);
 	}
-	splx(s);
 	return (revents);
 }
 
@@ -818,11 +792,10 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 	okeymap_t *omapp;
 	keyarg_t *keyp;
 	fkeyarg_t *fkeyp;
-	int s;
 	int i, j;
 	int error;
 
-	s = spltty();
+	GIANT_REQUIRED;
 	switch (cmd) {
 
 	case KDGKBINFO:		/* get keyboard information */
@@ -848,7 +821,6 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 	case GIO_KEYMAP:	/* get keyboard translation table */
 		error = copyout(kbd->kb_keymap, *(void **)arg,
 		    sizeof(keymap_t));
-		splx(s);
 		return (error);
 	case OGIO_KEYMAP:	/* get keyboard translation table (compat) */
 		mapp = kbd->kb_keymap;
@@ -879,7 +851,6 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		} else {
 			error = copyin(*(void **)arg, mapp, sizeof *mapp);
 			if (error != 0) {
-				splx(s);
 				free(mapp, M_TEMP);
 				return (error);
 			}
@@ -887,7 +858,6 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 
 		error = keymap_change_ok(kbd->kb_keymap, mapp, curthread);
 		if (error != 0) {
-			splx(s);
 			free(mapp, M_TEMP);
 			return (error);
 		}
@@ -896,7 +866,6 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		free(mapp, M_TEMP);
 		break;
 #else
-		splx(s);
 		return (ENODEV);
 #endif
 
@@ -904,7 +873,6 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		keyp = (keyarg_t *)arg;
 		if (keyp->keynum >= sizeof(kbd->kb_keymap->key) /
 		    sizeof(kbd->kb_keymap->key[0])) {
-			splx(s);
 			return (EINVAL);
 		}
 		bcopy(&kbd->kb_keymap->key[keyp->keynum], &keyp->key,
@@ -915,20 +883,17 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		keyp = (keyarg_t *)arg;
 		if (keyp->keynum >= sizeof(kbd->kb_keymap->key) /
 		    sizeof(kbd->kb_keymap->key[0])) {
-			splx(s);
 			return (EINVAL);
 		}
 		error = key_change_ok(&kbd->kb_keymap->key[keyp->keynum],
 		    &keyp->key, curthread);
 		if (error != 0) {
-			splx(s);
 			return (error);
 		}
 		bcopy(&keyp->key, &kbd->kb_keymap->key[keyp->keynum],
 		    sizeof(keyp->key));
 		break;
 #else
-		splx(s);
 		return (ENODEV);
 #endif
 
@@ -940,20 +905,17 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		error = accent_change_ok(kbd->kb_accentmap,
 		    (accentmap_t *)arg, curthread);
 		if (error != 0) {
-			splx(s);
 			return (error);
 		}
 		bcopy(arg, kbd->kb_accentmap, sizeof(*kbd->kb_accentmap));
 		break;
 #else
-		splx(s);
 		return (ENODEV);
 #endif
 
 	case GETFKEY:		/* get functionkey string */
 		fkeyp = (fkeyarg_t *)arg;
 		if (fkeyp->keynum >= kbd->kb_fkeytab_size) {
-			splx(s);
 			return (EINVAL);
 		}
 		bcopy(kbd->kb_fkeytab[fkeyp->keynum].str, fkeyp->keydef,
@@ -964,13 +926,11 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 #ifndef KBD_DISABLE_KEYMAP_LOAD
 		fkeyp = (fkeyarg_t *)arg;
 		if (fkeyp->keynum >= kbd->kb_fkeytab_size) {
-			splx(s);
 			return (EINVAL);
 		}
 		error = fkey_change_ok(&kbd->kb_fkeytab[fkeyp->keynum],
 		    fkeyp, curthread);
 		if (error != 0) {
-			splx(s);
 			return (error);
 		}
 		kbd->kb_fkeytab[fkeyp->keynum].len = min(fkeyp->flen, MAXFK);
@@ -978,16 +938,13 @@ genkbd_commonioctl(keyboard_t *kbd, u_long cmd, caddr_t arg)
 		    kbd->kb_fkeytab[fkeyp->keynum].len);
 		break;
 #else
-		splx(s);
 		return (ENODEV);
 #endif
 
 	default:
-		splx(s);
 		return (ENOIOCTL);
 	}
 
-	splx(s);
 	return (0);
 }