[PATCH 16/18] locking/atomic: use s64 for atomic64_t on 64-bit

[Mark Rutland]

Now that all architectures use 64 consistently as the base type for the
atomic64 API, let's have the CONFIG_64BIT definition of atomic64_t use
s64 as the underlying type for atomic64_t, rather than long, matching
the generated headers.

On architectures where atomic64_read(v) is READ_ONCE(v->counter), this
patch will cause the return type of atomic64_read() to be s64.

As of this patch, the atomic64 API can be relied upon to consistently
return s64 where a value rather than boolean condition is returned. This
should make code more robust, and simpler, allowing for the removal of
casts previously required to ensure consistent types.

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
---
 include/linux/types.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/types.h b/include/linux/types.h
index 231114ae38f4..05030f608be3 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -174,7 +174,7 @@ typedef struct {
 
 #ifdef CONFIG_64BIT
 typedef struct {
-	long counter;
+	s64 counter;
 } atomic64_t;
 #endif
 
-- 
2.11.0