ioctl: Add a macro for extracting the ioctl number from a command

Sprinkle it in various drivers which hard-coded the command layout.

No functional change intended.

Reviewed by:	dumbbell, emaste
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D61045

sys/compat/linuxkpi/common/include/linux/ioctl.h

@@ -33,6 +33,6 @@
 
 #define	_IOC_SIZE(cmd)	IOCPARM_LEN(cmd)
 #define	_IOC_TYPE(cmd)	IOCGROUP(cmd)
-#define	_IOC_NR(cmd)	((cmd) & 0xff)
+#define	_IOC_NR(cmd)	IOCNUM(cmd)
 
 #endif	/* _LINUXKPI_LINUX_IOCTL_H_ */

sys/dev/sound/pcm/dsp.c

@@ -565,7 +565,7 @@ dsp_ioctl_channel(struct dsp_cdevpriv *priv, struct pcm_channel *ch,
 
 	PCM_UNLOCKASSERT(d);
 
-	j = cmd & 0xff;
+	j = IOCNUM(cmd);
 
 	rdch = priv->rdch;
 	wrch = priv->wrch;

sys/dev/sound/pcm/mixer.c

@@ -912,7 +912,7 @@ mixer_ioctl_cmd(struct cdev *i_dev, unsigned long cmd, caddr_t arg, int mode,
 {
 	struct snd_mixer *m;
 	int ret = EINVAL, *arg_i = (int *)arg;
-	int v = -1, j = cmd & 0xff;
+	int v = -1, j = IOCNUM(cmd);
 
 	/*
 	 * Certain ioctls may be made on any type of device (audio, mixer,

sys/dev/syscons/scvesactl.c

@@ -54,9 +54,10 @@ static int
 vesa_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 {
 	scr_stat *scp;
-	int mode;
+	int mode, num;
 
 	scp = SC_STAT(tp);
+	num = IOCNUM(cmd);
 
 	switch (cmd) {
 	/* generic text modes */
@@ -65,7 +66,7 @@ vesa_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 	case SW_TEXT_132x60:
 		if (!(scp->sc->adp->va_flags & V_ADP_MODECHANGE))
 			return ENODEV;
-		return sc_set_text_mode(scp, tp, cmd & 0xff, 0, 0, 0, 0);
+		return sc_set_text_mode(scp, tp, num, 0, 0, 0, 0);
 
 	/* text modes */
 	case SW_VESA_C80x60:
@@ -75,7 +76,7 @@ vesa_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 	case SW_VESA_C132x60:
 		if (!(scp->sc->adp->va_flags & V_ADP_MODECHANGE))
 			return ENODEV;
-		mode = (cmd & 0xff) + M_VESA_BASE;
+		mode = num + M_VESA_BASE;
 		return sc_set_text_mode(scp, tp, mode, 0, 0, 0, 0);
 
 	/* graphics modes */
@@ -101,14 +102,14 @@ vesa_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 	case SW_VESA_FULL_1280:
 		if (!(scp->sc->adp->va_flags & V_ADP_MODECHANGE))
 			return ENODEV;
-		mode = (cmd & 0xff) + M_VESA_BASE;
+		mode = num + M_VESA_BASE;
 		return sc_set_graphics_mode(scp, tp, mode);
 	default:
 		if (IOCGROUP(cmd) == 'V') {
 			if (!(scp->sc->adp->va_flags & V_ADP_MODECHANGE))
 				return ENODEV;
 
-			mode = (cmd & 0xff) + M_VESA_BASE;
+			mode = num + M_VESA_BASE;
 
 			if (((cmd & IOC_DIRMASK) == IOC_VOID) &&
 			    (mode > M_VESA_FULL_1280) &&

sys/dev/syscons/scvidctl.c

@@ -651,7 +651,7 @@ sc_vid_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
     case SW_EGAMONO80x25:
 	if (!(adp->va_flags & V_ADP_MODECHANGE))
  	    return ENODEV;
-	return sc_set_text_mode(scp, tp, cmd & 0xff, 0, 0, 0, 0);
+	return sc_set_text_mode(scp, tp, IOCNUM(cmd), 0, 0, 0, 0);
 
     /* GRAPHICS MODES */
     case SW_BG320:     case SW_BG640:
@@ -661,7 +661,7 @@ sc_vid_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
     case SW_VGA_MODEX:
 	if (!(adp->va_flags & V_ADP_MODECHANGE))
 	    return ENODEV;
-	return sc_set_graphics_mode(scp, tp, cmd & 0xff);
+	return sc_set_graphics_mode(scp, tp, IOCNUM(cmd));
 #endif /* SC_NO_MODE_CHANGE */
 
 #if defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD5) || \

sys/netgraph/ng_eiface.c

@@ -332,7 +332,7 @@ ng_eiface_print_ioctl(struct ifnet *ifp, int command, caddr_t data)
 	    ifp->if_xname,
 	    str,
 	    IOCGROUP(command),
-	    command & 0xff,
+	    IOCNUM(command),
 	    IOCPARM_LEN(command));
 }
 #endif /* DEBUG */

sys/sys/ioccom.h

@@ -47,6 +47,7 @@
 #define	IOCPARM_LEN(x)	(((x) >> 16) & IOCPARM_MASK)
 #define	IOCBASECMD(x)	((x) & ~(IOCPARM_MASK << 16))
 #define	IOCGROUP(x)	(((x) >> 8) & 0xff)
+#define	IOCNUM(x)	((x) & 0xff)
 
 #define	IOCPARM_MAX	(1 << IOCPARM_SHIFT) /* max size of ioctl */