Commit 6ad56d51 authored by Vinod Koul's avatar Vinod Koul Committed by Greg Kroah-Hartman

linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL

[ Upstream commit 8f9fab480c7a87b10bb5440b5555f370272a5d59 ]

DIV_ROUND_UP_ULL adds the two arguments and then invokes
DIV_ROUND_DOWN_ULL.  But on a 32bit system the addition of two 32 bit
values can overflow.  DIV_ROUND_DOWN_ULL does it correctly and stashes
the addition into a unsigned long long so cast the result to unsigned
long long here to avoid the overflow condition.

[ DIV_ROUND_UP_ULL must be an rval]
Link: default avatarVinod Koul <>
Reviewed-by: default avatarAndrew Morton <>
Cc: Bjorn Andersson <>
Cc: Randy Dunlap <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
Signed-off-by: default avatarSasha Levin <>
parent 8f5e9235
......@@ -101,7 +101,8 @@
#define DIV_ROUND_DOWN_ULL(ll, d) \
({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
#define DIV_ROUND_UP_ULL(ll, d) DIV_ROUND_DOWN_ULL((ll) + (d) - 1, (d))
#define DIV_ROUND_UP_ULL(ll, d) \
DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d))
#if BITS_PER_LONG == 32
# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
Markdown is supported
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment