locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API

With the inclusion of atomic FETCH-OP variants, many places in the
kernel can make use of atomic_fetch_$op() to avoid the callers that
need to compute the value/state _before_ the operation.

Peter Zijlstra laid out the machinery but we are still missing the
simpler dec,inc() calls (which future patches will make use of).

This patch only deals with the generic code, as at least right now
no arch actually implement them -- which is similar to what the
OP-RETURN primitives currently do.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: James.Bottomley@HansenPartnership.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: awalls@md.metrocast.net
Cc: bp@alien8.de
Cc: cw00.choi@samsung.com
Cc: davem@davemloft.net
Cc: dledford@redhat.com
Cc: dougthompson@xmission.com
Cc: gregkh@linuxfoundation.org
Cc: hans.verkuil@cisco.com
Cc: heiko.carstens@de.ibm.com
Cc: jikos@kernel.org
Cc: kys@microsoft.com
Cc: mchehab@osg.samsung.com
Cc: pfg@sgi.com
Cc: schwidefsky@de.ibm.com
Cc: sean.hefty@intel.com
Cc: sumit.semwal@linaro.org
Link: http://lkml.kernel.org/r/20160628215651.GA20048@linux-80c1.suse
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/asm-generic/atomic-long.h

@@ -146,6 +146,28 @@ ATOMIC_LONG_FETCH_OP(xor, _relaxed)
 ATOMIC_LONG_FETCH_OP(xor, _acquire)
 ATOMIC_LONG_FETCH_OP(xor, _release)
 
+#undef ATOMIC_LONG_FETCH_OP
+
+#define ATOMIC_LONG_FETCH_INC_DEC_OP(op, mo)					\
+static inline long							\
+atomic_long_fetch_##op##mo(atomic_long_t *l)				\
+{									\
+	ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l;		\
+									\
+	return (long)ATOMIC_LONG_PFX(_fetch_##op##mo)(v);		\
+}
+
+ATOMIC_LONG_FETCH_INC_DEC_OP(inc,)
+ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _relaxed)
+ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _acquire)
+ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _release)
+ATOMIC_LONG_FETCH_INC_DEC_OP(dec,)
+ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _relaxed)
+ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _acquire)
+ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _release)
+
+#undef ATOMIC_LONG_FETCH_INC_DEC_OP
+
 #define ATOMIC_LONG_OP(op)						\
 static __always_inline void						\
 atomic_long_##op(long i, atomic_long_t *l)				\

include/linux/atomic.h

@@ -188,6 +188,38 @@
 #endif
 #endif /* atomic_fetch_add_relaxed */
 
+/* atomic_fetch_inc_relaxed */
+#ifndef atomic_fetch_inc_relaxed
+
+#ifndef atomic_fetch_inc
+#define atomic_fetch_inc(v)	        atomic_fetch_add(1, (v))
+#define atomic_fetch_inc_relaxed(v)	atomic_fetch_add_relaxed(1, (v))
+#define atomic_fetch_inc_acquire(v)	atomic_fetch_add_acquire(1, (v))
+#define atomic_fetch_inc_release(v)	atomic_fetch_add_release(1, (v))
+#else /* atomic_fetch_inc */
+#define atomic_fetch_inc_relaxed	atomic_fetch_inc
+#define atomic_fetch_inc_acquire	atomic_fetch_inc
+#define atomic_fetch_inc_release	atomic_fetch_inc
+#endif /* atomic_fetch_inc */
+
+#else /* atomic_fetch_inc_relaxed */
+
+#ifndef atomic_fetch_inc_acquire
+#define atomic_fetch_inc_acquire(...)					\
+	__atomic_op_acquire(atomic_fetch_inc, __VA_ARGS__)
+#endif
+
+#ifndef atomic_fetch_inc_release
+#define atomic_fetch_inc_release(...)					\
+	__atomic_op_release(atomic_fetch_inc, __VA_ARGS__)
+#endif
+
+#ifndef atomic_fetch_inc
+#define atomic_fetch_inc(...)						\
+	__atomic_op_fence(atomic_fetch_inc, __VA_ARGS__)
+#endif
+#endif /* atomic_fetch_inc_relaxed */
+
 /* atomic_fetch_sub_relaxed */
 #ifndef atomic_fetch_sub_relaxed
 #define atomic_fetch_sub_relaxed	atomic_fetch_sub
@@ -212,6 +244,38 @@
 #endif
 #endif /* atomic_fetch_sub_relaxed */
 
+/* atomic_fetch_dec_relaxed */
+#ifndef atomic_fetch_dec_relaxed
+
+#ifndef atomic_fetch_dec
+#define atomic_fetch_dec(v)	        atomic_fetch_sub(1, (v))
+#define atomic_fetch_dec_relaxed(v)	atomic_fetch_sub_relaxed(1, (v))
+#define atomic_fetch_dec_acquire(v)	atomic_fetch_sub_acquire(1, (v))
+#define atomic_fetch_dec_release(v)	atomic_fetch_sub_release(1, (v))
+#else /* atomic_fetch_dec */
+#define atomic_fetch_dec_relaxed	atomic_fetch_dec
+#define atomic_fetch_dec_acquire	atomic_fetch_dec
+#define atomic_fetch_dec_release	atomic_fetch_dec
+#endif /* atomic_fetch_dec */
+
+#else /* atomic_fetch_dec_relaxed */
+
+#ifndef atomic_fetch_dec_acquire
+#define atomic_fetch_dec_acquire(...)					\
+	__atomic_op_acquire(atomic_fetch_dec, __VA_ARGS__)
+#endif
+
+#ifndef atomic_fetch_dec_release
+#define atomic_fetch_dec_release(...)					\
+	__atomic_op_release(atomic_fetch_dec, __VA_ARGS__)
+#endif
+
+#ifndef atomic_fetch_dec
+#define atomic_fetch_dec(...)						\
+	__atomic_op_fence(atomic_fetch_dec, __VA_ARGS__)
+#endif
+#endif /* atomic_fetch_dec_relaxed */
+
 /* atomic_fetch_or_relaxed */
 #ifndef atomic_fetch_or_relaxed
 #define atomic_fetch_or_relaxed	atomic_fetch_or
@@ -697,6 +761,38 @@ static inline int atomic_dec_if_positive(atomic_t *v)
 #endif
 #endif /* atomic64_fetch_add_relaxed */
 
+/* atomic64_fetch_inc_relaxed */
+#ifndef atomic64_fetch_inc_relaxed
+
+#ifndef atomic64_fetch_inc
+#define atomic64_fetch_inc(v)		atomic64_fetch_add(1, (v))
+#define atomic64_fetch_inc_relaxed(v)	atomic64_fetch_add_relaxed(1, (v))
+#define atomic64_fetch_inc_acquire(v)	atomic64_fetch_add_acquire(1, (v))
+#define atomic64_fetch_inc_release(v)	atomic64_fetch_add_release(1, (v))
+#else /* atomic64_fetch_inc */
+#define atomic64_fetch_inc_relaxed	atomic64_fetch_inc
+#define atomic64_fetch_inc_acquire	atomic64_fetch_inc
+#define atomic64_fetch_inc_release	atomic64_fetch_inc
+#endif /* atomic64_fetch_inc */
+
+#else /* atomic64_fetch_inc_relaxed */
+
+#ifndef atomic64_fetch_inc_acquire
+#define atomic64_fetch_inc_acquire(...)					\
+	__atomic_op_acquire(atomic64_fetch_inc, __VA_ARGS__)
+#endif
+
+#ifndef atomic64_fetch_inc_release
+#define atomic64_fetch_inc_release(...)					\
+	__atomic_op_release(atomic64_fetch_inc, __VA_ARGS__)
+#endif
+
+#ifndef atomic64_fetch_inc
+#define atomic64_fetch_inc(...)						\
+	__atomic_op_fence(atomic64_fetch_inc, __VA_ARGS__)
+#endif
+#endif /* atomic64_fetch_inc_relaxed */
+
 /* atomic64_fetch_sub_relaxed */
 #ifndef atomic64_fetch_sub_relaxed
 #define atomic64_fetch_sub_relaxed	atomic64_fetch_sub
@@ -721,6 +817,38 @@ static inline int atomic_dec_if_positive(atomic_t *v)
 #endif
 #endif /* atomic64_fetch_sub_relaxed */
 
+/* atomic64_fetch_dec_relaxed */
+#ifndef atomic64_fetch_dec_relaxed
+
+#ifndef atomic64_fetch_dec
+#define atomic64_fetch_dec(v)		atomic64_fetch_sub(1, (v))
+#define atomic64_fetch_dec_relaxed(v)	atomic64_fetch_sub_relaxed(1, (v))
+#define atomic64_fetch_dec_acquire(v)	atomic64_fetch_sub_acquire(1, (v))
+#define atomic64_fetch_dec_release(v)	atomic64_fetch_sub_release(1, (v))
+#else /* atomic64_fetch_dec */
+#define atomic64_fetch_dec_relaxed	atomic64_fetch_dec
+#define atomic64_fetch_dec_acquire	atomic64_fetch_dec
+#define atomic64_fetch_dec_release	atomic64_fetch_dec
+#endif /* atomic64_fetch_dec */
+
+#else /* atomic64_fetch_dec_relaxed */
+
+#ifndef atomic64_fetch_dec_acquire
+#define atomic64_fetch_dec_acquire(...)					\
+	__atomic_op_acquire(atomic64_fetch_dec, __VA_ARGS__)
+#endif
+
+#ifndef atomic64_fetch_dec_release
+#define atomic64_fetch_dec_release(...)					\
+	__atomic_op_release(atomic64_fetch_dec, __VA_ARGS__)
+#endif
+
+#ifndef atomic64_fetch_dec
+#define atomic64_fetch_dec(...)						\
+	__atomic_op_fence(atomic64_fetch_dec, __VA_ARGS__)
+#endif
+#endif /* atomic64_fetch_dec_relaxed */
+
 /* atomic64_fetch_or_relaxed */
 #ifndef atomic64_fetch_or_relaxed
 #define atomic64_fetch_or_relaxed	atomic64_fetch_or