Commit-ID:  1ba9a294141b106b7247649a5c3372d8284eca80
Gitweb:     http://git.kernel.org/tip/1ba9a294141b106b7247649a5c3372d8284eca80
Author:     Jan Beulich <[email protected]>
AuthorDate: Fri, 6 Jul 2012 15:07:48 +0100
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 10 Jul 2012 10:38:14 +0200

x86/mm/mtrr: Fix alignment determination in range_to_mtrr()

With the variable operated on being of "unsigned long" type,
neither ffs() nor fls() are suitable to use on them, as those
truncate their arguments to 32 bits. Using __ffs() and __fls()
respectively at once eliminates the need to subtract 1 from their
results.

Additionally, with the alignment value subsequently used as a
shift count, it must be enforced to be less than BITS_PER_LONG
(and on 64-bit there's no need for it to be any smaller).

Signed-off-by: Jan Beulich <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Yinghai Lu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/kernel/cpu/mtrr/cleanup.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c 
b/arch/x86/kernel/cpu/mtrr/cleanup.c
index bdda2e6..35ffda5 100644
--- a/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ b/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -258,11 +258,11 @@ range_to_mtrr(unsigned int reg, unsigned long 
range_startk,
 
                /* Compute the maximum size with which we can make a range: */
                if (range_startk)
-                       max_align = ffs(range_startk) - 1;
+                       max_align = __ffs(range_startk);
                else
-                       max_align = 32;
+                       max_align = BITS_PER_LONG - 1;
 
-               align = fls(range_sizek) - 1;
+               align = __fls(range_sizek);
                if (align > max_align)
                        align = max_align;
 
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