[PATCHv2 1/2] mtd: mtdchar.c silence sparse warning

[Harvey Harrison <harvey.harrison@gmail.com>]

The copy_to_user was casting away the address space to get the offset
of the length member.  Use offsetof() instead and add it to the void __user *argp.

drivers/mtd/mtdchar.c:527:23: warning: cast removes address space of expression
drivers/mtd/mtdchar.c:527:23: warning: incorrect type in argument 1 (different address spaces)
drivers/mtd/mtdchar.c:527:23:    expected void [noderef] <asn:1>*to
drivers/mtd/mtdchar.c:527:23:    got unsigned int *<noident>

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
 drivers/mtd/mtdchar.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 5d3ac51..9c2af46 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -481,6 +481,7 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
 	{
 		struct mtd_oob_buf buf;
 		struct mtd_oob_ops ops;
+		struct mtd_oob_buf __user *user_buf = argp;
 	        uint32_t retlen;
 
 		if(!(file->f_mode & 2))
@@ -524,8 +525,7 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
 		if (ops.oobretlen > 0xFFFFFFFFU)
 			ret = -EOVERFLOW;
 		retlen = ops.oobretlen;
-		if (copy_to_user(&((struct mtd_oob_buf *)argp)->length,
-				 &retlen, sizeof(buf.length)))
+		if (copy_to_user(&user_buf->length, &retlen, sizeof(buf.length)))
 			ret = -EFAULT;
 
 		kfree(ops.oobbuf);
-- 
1.5.5.1.482.g0f174