linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL
authorVinod Koul <vkoul@kernel.org>
Fri, 28 Jun 2019 19:07:21 +0000 (12:07 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 29 Jun 2019 08:43:45 +0000 (16:43 +0800)
commit8f9fab480c7a87b10bb5440b5555f370272a5d59
treea7980854d30c6713bfc9ca225fb1f79fc6274327
parent1a5f439c7c02837d943e528d46501564d4226757
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.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/kernel.h