linux-kernel - [PATCH 16/18] locking/atomic: use s64 for atomic64

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Message-Id: <20190522132250.26499-17-mark.rutland@arm.com>
Date:   Wed, 22 May 2019 14:22:48 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        will.deacon@....com
Cc:     aou@...s.berkeley.edu, arnd@...db.de, bp@...en8.de,
        catalin.marinas@....com, davem@...emloft.net, fenghua.yu@...el.com,
        heiko.carstens@...ibm.com, herbert@...dor.apana.org.au,
        ink@...assic.park.msu.ru, jhogan@...nel.org, linux@...linux.org.uk,
        mark.rutland@....com, mattst88@...il.com, mingo@...nel.org,
        mpe@...erman.id.au, palmer@...ive.com, paul.burton@...s.com,
        paulus@...ba.org, ralf@...ux-mips.org, rth@...ddle.net,
        stable@...r.kernel.org, tglx@...utronix.de, tony.luck@...el.com,
        vgupta@...opsys.com
Subject: [PATCH 16/18] 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@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will.deacon@....com>
---
 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