From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Boris Brezillon <boris.brezillon@bootlin.com>,
Richard Weinberger <richard@nod.at>,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Marek Vasut <marek.vasut@gmail.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
linux-mtd@lists.infradead.org, linux-m68k@vger.kernel.org,
linux-kernel@vger.kernel.org,
Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH] mtd: nand: Fix return type of __DIVIDE() when called with 32-bit
Date: Mon, 14 May 2018 12:49:37 +0200 [thread overview]
Message-ID: <1526294977-32303-1-git-send-email-geert@linux-m68k.org> (raw)
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 64-bit division to the type of the
dividend.
Fixes: 8878b126df769831 ("mtd: nand: add ->exec_op() implementation")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
This fixes the root cause of the link failure seen with
m68k/allmodconfig since commit 3057fcef385348fe ("mtd: rawnand: Make
sure we wait tWB before polling the STATUS reg").
An alternative mitigation was posted as "[PATCH] m68k: Implement
ndelay() as an inline function to force type checking/casting"
(https://lkml.org/lkml/2018/5/13/102).
---
include/linux/mtd/rawnand.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 5dad59b312440a9c..d06dc428ea0102ae 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -871,7 +871,7 @@ struct nand_op_instr {
#define __DIVIDE(dividend, divisor) ({ \
sizeof(dividend) == sizeof(u32) ? \
DIV_ROUND_UP(dividend, divisor) : \
- DIV_ROUND_UP_ULL(dividend, divisor); \
+ (__typeof__(dividend))DIV_ROUND_UP_ULL(dividend, divisor); \
})
#define PSEC_TO_NSEC(x) __DIVIDE(x, 1000)
#define PSEC_TO_MSEC(x) __DIVIDE(x, 1000000000)
--
2.7.4
next reply other threads:[~2018-05-14 10:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-14 10:49 Geert Uytterhoeven [this message]
2018-05-14 11:23 ` [PATCH] mtd: nand: Fix return type of __DIVIDE() when called with 32-bit Boris Brezillon
2018-05-14 11:32 ` Geert Uytterhoeven
2018-05-14 11:46 ` Boris Brezillon
2018-05-14 11:55 ` Boris Brezillon
2018-05-14 12:00 ` Geert Uytterhoeven
2018-05-14 12:13 ` Boris Brezillon
2018-05-14 12:48 ` Geert Uytterhoeven
2018-05-15 9:12 ` Boris Brezillon
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