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author | Martin K. Petersen <martin.petersen@oracle.com> | 2010-03-15 12:46:51 +0100 |
---|---|---|
committer | Jens Axboe <jens.axboe@oracle.com> | 2010-03-15 12:47:59 +0100 |
commit | 2cda2728aa1c8c006418a24f867b25e5eb7a32e2 (patch) | |
tree | c23ec7c38d74237646c5453d96bfbbea4cadfee7 | |
parent | f11c9c5c259cb2c3d698548dc3936f773ab1f5b9 (diff) | |
download | kernel_samsung_tuna-2cda2728aa1c8c006418a24f867b25e5eb7a32e2.zip kernel_samsung_tuna-2cda2728aa1c8c006418a24f867b25e5eb7a32e2.tar.gz kernel_samsung_tuna-2cda2728aa1c8c006418a24f867b25e5eb7a32e2.tar.bz2 |
block: Fix overrun in lcm() and move it to lib
lcm() was defined to take integer-sized arguments. The supplied
arguments are multiplied, however, causing us to overflow given
sufficiently large input. That in turn led to incorrect optimal I/O
size reporting in some cases (RAID over RAID).
Switch lcm() over to unsigned long similar to gcd() and move the
function from blk-settings.c to lib.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r-- | block/blk-settings.c | 11 | ||||
-rw-r--r-- | include/linux/lcm.h | 8 | ||||
-rw-r--r-- | lib/Makefile | 2 | ||||
-rw-r--r-- | lib/lcm.c | 15 |
4 files changed, 25 insertions, 11 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 31e7a93..4c4700d 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -8,6 +8,7 @@ #include <linux/blkdev.h> #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ #include <linux/gcd.h> +#include <linux/lcm.h> #include <linux/jiffies.h> #include "blk.h" @@ -461,16 +462,6 @@ void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) } EXPORT_SYMBOL(blk_queue_stack_limits); -static unsigned int lcm(unsigned int a, unsigned int b) -{ - if (a && b) - return (a * b) / gcd(a, b); - else if (b) - return b; - - return a; -} - /** * blk_stack_limits - adjust queue_limits for stacked devices * @t: the stacking driver limits (top device) diff --git a/include/linux/lcm.h b/include/linux/lcm.h new file mode 100644 index 0000000..7bf01d7 --- /dev/null +++ b/include/linux/lcm.h @@ -0,0 +1,8 @@ +#ifndef _LCM_H +#define _LCM_H + +#include <linux/compiler.h> + +unsigned long lcm(unsigned long a, unsigned long b) __attribute_const__; + +#endif /* _LCM_H */ diff --git a/lib/Makefile b/lib/Makefile index 2e152ae..0d40152 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -21,7 +21,7 @@ lib-y += kobject.o kref.o klist.o obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \ bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \ - string_helpers.o gcd.o list_sort.o + string_helpers.o gcd.o lcm.o list_sort.o ifeq ($(CONFIG_DEBUG_KOBJECT),y) CFLAGS_kobject.o += -DDEBUG diff --git a/lib/lcm.c b/lib/lcm.c new file mode 100644 index 0000000..157cd88 --- /dev/null +++ b/lib/lcm.c @@ -0,0 +1,15 @@ +#include <linux/kernel.h> +#include <linux/gcd.h> +#include <linux/module.h> + +/* Lowest common multiple */ +unsigned long lcm(unsigned long a, unsigned long b) +{ + if (a && b) + return (a * b) / gcd(a, b); + else if (b) + return b; + + return a; +} +EXPORT_SYMBOL_GPL(lcm); |