4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
[ Upstream commit 9f825e74d761c13b0cfaa5f65344d64ff970e252 ]
The __DIVIDE() macro checks whether it is called with a 32-bit or 64-bit
dividend, to select the appropriate divide-and-round-up routine.
As the check uses the ternary operator, the result will always be
promoted to a type that can hold both results, i.e. unsigned long long.
When using this result in a division on a 32-bit system, this may lead
to link errors like:
ERROR: "__udivdi3" [drivers/mtd/nand/raw/nand.ko] undefined!
Fix this by casting the result of the division to the type of the
dividend.
Fixes: 8878b126df769831 ("mtd: nand: add ->exec_op() implementation")
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/mtd/rawnand.h | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -824,12 +824,18 @@ struct nand_op_instr {
* tBERS (during an erase) which all of them are u64 values that cannot be
* divided by usual kernel macros and must be handled with the special
* DIV_ROUND_UP_ULL() macro.
+ *
+ * Cast to type of dividend is needed here to guarantee that the result won't
+ * be an unsigned long long when the dividend is an unsigned long (or smaller),
+ * which is what the compiler does when it sees ternary operator with 2
+ * different return types (picks the largest type to make sure there's no
+ * loss).
*/
-#define __DIVIDE(dividend, divisor) ({ \
- sizeof(dividend) == sizeof(u32) ? \
- DIV_ROUND_UP(dividend, divisor) : \
- DIV_ROUND_UP_ULL(dividend, divisor); \
- })
+#define __DIVIDE(dividend, divisor) ({ \
+ (__typeof__(dividend))(sizeof(dividend) <= sizeof(unsigned long) ? \
+ DIV_ROUND_UP(dividend, divisor) : \
+ DIV_ROUND_UP_ULL(dividend, divisor)); \
+ })
#define PSEC_TO_NSEC(x) __DIVIDE(x, 1000)
#define PSEC_TO_MSEC(x) __DIVIDE(x, 1000000000)
