x86: fix spin_is_contended()
The masked difference is what needs to be compared against 1, rather
than the difference of masked values (which can be negative).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/spinlock.h b/include/asm-x86/spinlock.h
index 4f9a986..e39c790 100644
--- a/include/asm-x86/spinlock.h
+++ b/include/asm-x86/spinlock.h
@@ -65,7 +65,7 @@
{
int tmp = ACCESS_ONCE(lock->slock);
- return (((tmp >> 8) & 0xff) - (tmp & 0xff)) > 1;
+ return (((tmp >> 8) - tmp) & 0xff) > 1;
}
static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock)
@@ -127,7 +127,7 @@
{
int tmp = ACCESS_ONCE(lock->slock);
- return (((tmp >> 16) & 0xffff) - (tmp & 0xffff)) > 1;
+ return (((tmp >> 16) - tmp) & 0xffff) > 1;
}
static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock)