4.16-stable review patch. If anyone has any objections, please let me know.
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From: Geert Uytterhoeven geert@linux-m68k.org
[ 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@linux-m68k.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)