[PATCH] rework reserved major handling

Several people have reported failures in dynamic major device number handling
due to the recent changes in there to avoid handing out the local/experimental
majors.

Rolf reports that this is due to a gcc-4.1.0 bug.

The patch refactors that code a lot in an attempt to provoke the compiler into
behaving.

Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

block/genhd.c

@@ -5,6 +5,7 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/genhd.h>
+#include <linux/kdev_t.h>
 #include <linux/kernel.h>
 #include <linux/blkdev.h>
 #include <linux/init.h>
@@ -61,13 +62,7 @@ int register_blkdev(unsigned int major, const char *name)
 	/* temporary */
 	if (major == 0) {
 		for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
-			/*
-			 * Disallow the LANANA-assigned LOCAL/EXPERIMENTAL
-			 * majors
-			 */
-			if ((60 <= index && index <= 63) ||
-					(120 <= index && index <= 127) ||
-					(240 <= index && index <= 254))
+			if (is_lanana_major(index))
 				continue;
 			if (major_names[index] == NULL)
 				break;

drivers/base/core.c

@@ -27,6 +27,20 @@
 int (*platform_notify)(struct device * dev) = NULL;
 int (*platform_notify_remove)(struct device * dev) = NULL;
 
+/*
+ * Detect the LANANA-assigned LOCAL/EXPERIMENTAL majors
+ */
+bool is_lanana_major(unsigned int major)
+{
+	if (major >= 60 && major <= 63)
+		return 1;
+	if (major >= 120 && major <= 127)
+		return 1;
+	if (major >= 240 && major <= 254)
+		return 1;
+	return 0;
+}
+
 /*
  * sysfs bindings for devices.
  */

fs/char_dev.c

@@ -6,6 +6,7 @@
 
 #include <linux/init.h>
 #include <linux/fs.h>
+#include <linux/kdev_t.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
@@ -108,12 +109,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 	/* temporary */
 	if (major == 0) {
 		for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
-			/*
-			 * Disallow the LANANA-assigned LOCAL/EXPERIMENTAL
-			 * majors
-			 */
-			if ((60 <= i && i <= 63) || (120 <= i && i <= 127) ||
-					(240 <= i && i <= 254))
+			if (is_lanana_major(i))
 				continue;
 			if (chrdevs[i] == NULL)
 				break;

include/linux/kdev_t.h

@@ -87,6 +87,7 @@ static inline unsigned sysv_minor(u32 dev)
 	return dev & 0x3ffff;
 }
 
+bool is_lanana_major(unsigned int major);
 
 #else /* __KERNEL__ */