mtd: rawnand: Fix return type of __DIVIDE() when called with 32-bit (9f825e74) · Commits · 戴 / test

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: ("mtd: nand: add ->exec_op() implementation") Signed-off-by:

Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by:

Boris Brezillon <boris.brezillon@bootlin.com>

include/linux/mtd/rawnand.h

+11 −5

Original line number	Diff line number	Diff line
		@@ -867,11 +867,17 @@ 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) ? \
		(__typeof__(dividend))(sizeof(dividend) <= sizeof(unsigned long) ? \
		DIV_ROUND_UP(dividend, divisor) : \
		DIV_ROUND_UP_ULL(dividend, divisor); \
		DIV_ROUND_UP_ULL(dividend, divisor)); \
		})
		#define PSEC_TO_NSEC(x) __DIVIDE(x, 1000)
		#define PSEC_TO_MSEC(x) __DIVIDE(x, 1000000000)

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