BUG: physmap modprobe & rmmod

[H Hartley Sweeten]

On Friday, April 02, 2010 2:47 PM, Randy Dunlap wrote:
>> 2.6.34-rc2 kernel:
>> 
>> Boot up on a common PC, then: modprobe physmap ; rmmod physmap
>> and bang.

[snip]

> This is with close to an allmodconfig on x86_64, including:
> 
> CONFIG_MTD_PHYSMAP=m
> CONFIG_MTD_PHYSMAP_COMPAT=y
> CONFIG_MTD_PHYSMAP_START=0x8000000
> CONFIG_MTD_PHYSMAP_LEN=0
> CONFIG_MTD_PHYSMAP_BANKWIDTH=2

That's probably the cause of the BUG.

If your not run-time calling physmap_configure(), your resource will
be created as:

static struct physmap_flash_data physmap_flash_data = {
	.width		= CONFIG_MTD_PHYSMAP_BANKWIDTH,
};

static struct resource physmap_flash_resource = {
	.start		= CONFIG_MTD_PHYSMAP_START,
	.end		= CONFIG_MTD_PHYSMAP_START + CONFIG_MTD_PHYSMAP_LEN - 1,
	.flags		= IORESOURCE_MEM,
};

In other words:

static struct physmap_flash_data physmap_flash_data = {
	.width		= 2,
};

static struct resource physmap_flash_resource = {
	.start		= 0x8000000,
	.end		= 0x8000000 + 0 - 1,
	.flags		= IORESOURCE_MEM,
};

I don't think your even getting into the physmap_flash_probe routine.
Your probably getting the BUG after:

	platform_device_register(&physmap_flash);

Which eventually gets to platform_device_add which is giving you the
message:

> [  127.869454] physmap-flash.0: failed to claim resource 0

Try this patch to see if it fixes your BUG.

---

mtd/maps/physmap: catch failure to register MTD_PHYSMAP_COMPAT device

If the default Kconfig values are used with MTD_PHYSMAP_COMPAT you end
up with a IORESOURCE_MEM of 0 size.  This causes platform_device_add
to fail during the platform_device_register call.

Catch this failure during the physmap_init.

Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>

---

diff --git a/drivers/mtd/maps/physmap.c b/drivers/mtd/maps/physmap.c
index d9603f7..426461a 100644
--- a/drivers/mtd/maps/physmap.c
+++ b/drivers/mtd/maps/physmap.c
@@ -264,8 +264,11 @@ static int __init physmap_init(void)
 
 	err = platform_driver_register(&physmap_flash_driver);
 #ifdef CONFIG_MTD_PHYSMAP_COMPAT
-	if (err == 0)
-		platform_device_register(&physmap_flash);
+	if (err == 0) {
+		err = platform_device_register(&physmap_flash);
+		if (err)
+			platform_driver_unregister(&physmap_flash_driver);
+	}
 #endif
 
 	return err;