Commit 8f9fab48 authored by Vinod Koul's avatar Vinod Koul Committed by Linus Torvalds

linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL

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.

[akpm@linux-foundation.org: DIV_ROUND_UP_ULL must be an rval]
Link: http://lkml.kernel.org/r/20190625100518.30753-1-vkoul@kernel.orgSigned-off-by: default avatarVinod Koul <vkoul@kernel.org>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1a5f439c
...@@ -93,7 +93,8 @@ ...@@ -93,7 +93,8 @@
#define DIV_ROUND_DOWN_ULL(ll, d) \ #define DIV_ROUND_DOWN_ULL(ll, d) \
({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; }) ({ 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 #if BITS_PER_LONG == 32
# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d) # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
......
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