[tip:locking/core] locking/atomic: Use s64 for atomic64_t on 64-bit

[tip-bot for Mark Rutland]

Commit-ID:  3724921396dd1a07c93e3516b8d7c9ff570d17a9
Gitweb:     https://git.kernel.org/tip/3724921396dd1a07c93e3516b8d7c9ff570d17a9
Author:     Mark Rutland <mark.rutland@xxxxxxx>
AuthorDate: Wed, 22 May 2019 14:22:48 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Jun 2019 12:32:57 +0200

locking/atomic: Use s64 for atomic64_t on 64-bit

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: aou@xxxxxxxxxxxxxxxxx
Cc: arnd@xxxxxxxx
Cc: bp@xxxxxxxxx
Cc: catalin.marinas@xxxxxxx
Cc: davem@xxxxxxxxxxxxx
Cc: fenghua.yu@xxxxxxxxx
Cc: heiko.carstens@xxxxxxxxxx
Cc: herbert@xxxxxxxxxxxxxxxxxxx
Cc: ink@xxxxxxxxxxxxxxxxxxxx
Cc: jhogan@xxxxxxxxxx
Cc: linux@xxxxxxxxxxxxxxx
Cc: mattst88@xxxxxxxxx
Cc: mpe@xxxxxxxxxxxxxx
Cc: palmer@xxxxxxxxxx
Cc: paul.burton@xxxxxxxx
Cc: paulus@xxxxxxxxx
Cc: ralf@xxxxxxxxxxxxxx
Cc: rth@xxxxxxxxxxx
Cc: tony.luck@xxxxxxxxx
Cc: vgupta@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20190522132250.26499-17-mark.rutland@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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