[MTD] Deal correctly with NOR chips which are smaller than the map window

[Linux-MTD Mailing List]

commit 0f5ae3d2e9f49af55eb2a9b7cb54b4c0c2373017
tree c06f26d34bff12e4324e901a6406835894010da3
parent a6550e57f9d074511cf420bdb802ab5e56edc3bb
author David Woodhouse <dwmw2 at infradead.org> Sun, 14 May 2006 01:40:50 +0100
committer David Woodhouse <dwmw2 at infradead.org> Sun, 14 May 2006 01:40:50 +0100

[MTD] Deal correctly with NOR chips which are smaller than the map window

We used to calculate the number of chips to be zero, allocate an array
of that size, then nasty things would happen when we attempt to access
the first object in that zero-sized array.

Now, if the number of _full_ chips that would fit into the map is zero,
we allocate an array of one anyway, and then artificially reduce the
total size of the resulting MTD device to fit in the map.

Signed-off-by: David Woodhouse <dwmw2 at infradead.org>

 drivers/mtd/chips/gen_probe.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/chips/gen_probe.c b/drivers/mtd/chips/gen_probe.c
index 9b252d2..b2d3052 100644
--- a/drivers/mtd/chips/gen_probe.c
+++ b/drivers/mtd/chips/gen_probe.c
@@ -37,8 +37,15 @@ struct mtd_info *mtd_do_chip_probe(struc
 	if (!mtd)
 		mtd = check_cmd_set(map, 0); /* Then the secondary */
 
-	if (mtd)
+	if (mtd) {
+		if (mtd->size > map->size) {
+			printk(KERN_WARNING "Reducing visibility of %lKiB chip to %lKiB\n",
+			       (unsigned long)mtd->size >> 10, 
+			       (unsigned long)map->size >> 10);
+			mtd->size = map->size;
+		}
 		return mtd;
+	}
 
 	printk(KERN_WARNING"gen_probe: No supported Vendor Command Set found\n");
 
@@ -100,7 +107,12 @@ #endif
 	 * Align bitmap storage size to full byte.
 	 */
 	max_chips = map->size >> cfi.chipshift;
-	mapsize = (max_chips / 8) + ((max_chips % 8) ? 1 : 0);
+	if (!max_chips) {
+		printk(KERN_WARNING "NOR chip too large to fit in mapping. Attempting to cope...\n");
+		max_chips = 1;
+	}
+
+	mapsize = (max_chips + BITS_PER_LONG-1) / BITS_PER_LONG;
 	chip_map = kmalloc(mapsize, GFP_KERNEL);
 	if (!chip_map) {
 		printk(KERN_WARNING "%s: kmalloc failed for CFI chip map\n", map->name);