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 <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/4FF70D54020000780008E179@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c
index bdda2e6c673bf71afb30ed670071a9d02dbdcbfa..35ffda5d0727d19b11cccccdde0e0d461b9e15ee 100644 (file)
--- 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;