[PATCH] mtd cmdlinepart: allow zero offset value

Current cmdlinepart.c uses offset value 0 to specify a continuous
partition.  This prevents creating a second partition starting at 0.

For example, I can split 4MB device using "mtdparts=id:2M,2M", but I can
not do "mtdparts=id:2M@2M,2M@0" to swap mtd0 and mtd1.

This patch introduces special OFFSET_CONTINUOUS value for a continuous
partition and allows 0 for offset value.

Also this patch replaces 0xffffffff with UINT_MAX for SIZE_REMAINING.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: NDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/mtd/cmdlinepart.c

@@ -42,7 +42,8 @@
 
 
 /* special size referring to all the remaining space in a partition */
-#define SIZE_REMAINING 0xffffffff
+#define SIZE_REMAINING UINT_MAX
+#define OFFSET_CONTINUOUS UINT_MAX
 
 struct cmdline_mtd_partition {
 	struct cmdline_mtd_partition *next;
@@ -75,7 +76,7 @@ static struct mtd_partition * newpart(char *s,
 {
 	struct mtd_partition *parts;
 	unsigned long size;
-	unsigned long offset = 0;
+	unsigned long offset = OFFSET_CONTINUOUS;
 	char *name;
 	int name_len;
 	unsigned char *extra_mem;
@@ -314,7 +315,7 @@ static int parse_cmdline_partitions(struct mtd_info *master,
 		{
 			for(i = 0, offset = 0; i < part->num_parts; i++)
 			{
-				if (!part->parts[i].offset)
+				if (part->parts[i].offset == OFFSET_CONTINUOUS)
 				  part->parts[i].offset = offset;
 				else
 				  offset = part->parts[i].offset;