[ 06/64] MIPS: Fix logic errors in bitops.c

From: Greg Kroah-Hartman
Date: Wed Apr 10 2013 - 19:18:28 EST


3.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: David Daney <david.daney@xxxxxxxxxx>

commit 0c81157b46c533139d6be721d41617020c59a2c3 upstream.

commit 92d11594f6 (MIPS: Remove irqflags.h dependency from bitops.h)
factored some of the bitops code out into a separate file
(arch/mips/lib/bitops.c). Unfortunately the logic converting a bit
mask into a boolean result was lost in some of the functions. We had:

int res;
unsigned long shifted_result_bit;
.
.
.
res = shifted_result_bit;
return res;

Which truncates off the high 32 bits (thus yielding an incorrect
value) on 64-bit systems.

The manifestation of this is that a non-SMP 64-bit kernel will not
boot as the bitmap operations in bootmem.c are all screwed up.

Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: Jim Quinlan <jim2101024@xxxxxxxxx>
Patchwork: https://patchwork.linux-mips.org/patch/4965/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/mips/lib/bitops.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

--- a/arch/mips/lib/bitops.c
+++ b/arch/mips/lib/bitops.c
@@ -90,12 +90,12 @@ int __mips_test_and_set_bit(unsigned lon
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
- unsigned long res;
+ int res;

a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
- res = (mask & *a);
+ res = (mask & *a) != 0;
*a |= mask;
raw_local_irq_restore(flags);
return res;
@@ -116,12 +116,12 @@ int __mips_test_and_set_bit_lock(unsigne
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
- unsigned long res;
+ int res;

a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
- res = (mask & *a);
+ res = (mask & *a) != 0;
*a |= mask;
raw_local_irq_restore(flags);
return res;
@@ -141,12 +141,12 @@ int __mips_test_and_clear_bit(unsigned l
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
- unsigned long res;
+ int res;

a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
- res = (mask & *a);
+ res = (mask & *a) != 0;
*a &= ~mask;
raw_local_irq_restore(flags);
return res;
@@ -166,12 +166,12 @@ int __mips_test_and_change_bit(unsigned
unsigned bit = nr & SZLONG_MASK;
unsigned long mask;
unsigned long flags;
- unsigned long res;
+ int res;

a += nr >> SZLONG_LOG;
mask = 1UL << bit;
raw_local_irq_save(flags);
- res = (mask & *a);
+ res = (mask & *a) != 0;
*a ^= mask;
raw_local_irq_restore(flags);
return res;


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