[PATCH] make local_t signed

local_t's were defined to be unsigned.  This increases confusion because
atomic_t's are signed.  The patch goes through and changes all implementations
to use signed longs throughout.

Also, x86-64 was using 32-bit quantities for the value passed into local_add()
and local_sub().  Fixed.

All (actually, both) existing users have been audited.

(Also s/__inline__/inline/ in x86_64/local.h)

Cc: Andi Kleen <ak@muc.de>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 3 deletions

diff --git a/include/asm-generic/local.h b/include/asm-generic/local.h
index de4614840c2c..9291c24f5819 100644
--- a/include/asm-generic/local.h
+++ b/include/asm-generic/local.h
@@ -7,8 +7,15 @@
 #include <asm/atomic.h>
 #include <asm/types.h>
 
-/* An unsigned long type for operations which are atomic for a single
- * CPU.  Usually used in combination with per-cpu variables. */
+/*
+ * A signed long type for operations which are atomic for a single CPU.
+ * Usually used in combination with per-cpu variables.
+ *
+ * This is the default implementation, which uses atomic_long_t.  Which is
+ * rather pointless.  The whole point behind local_t is that some processors
+ * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
+ * running on this CPU.  local_t allows exploitation of such capabilities.
+ */
 
 /* Implement in terms of atomics. */
 
@@ -20,7 +27,7 @@ typedef struct
 
 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
 
-#define local_read(l)   ((unsigned long)atomic_long_read(&(l)->a))
+#define local_read(l)   atomic_long_read(&(l)->a)
 #define local_set(l,i)  atomic_long_set((&(l)->a),(i))
 #define local_inc(l)    atomic_long_inc(&(l)->a)
 #define local_dec(l)    atomic_long_dec(&(l)->a)