linux-kernel - [PATCH 5/6] MIPS: Provide {atomic_}xchg

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Date:   Wed, 27 Jan 2021 21:36:26 +0100
From:   Alexander A Sverdlin <alexander.sverdlin@...ia.com>
To:     Paul Burton <paul.burton@...tec.com>, linux-mips@...r.kernel.org
Cc:     Alexander Sverdlin <alexander.sverdlin@...ia.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 5/6] MIPS: Provide {atomic_}xchg_relaxed()

From: Alexander Sverdlin <alexander.sverdlin@...ia.com>

This has the effect of removing one redundant SYNCW from
queued_spin_lock_slowpath() on Octeon.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...ia.com>
---
 arch/mips/include/asm/atomic.h  | 2 ++
 arch/mips/include/asm/cmpxchg.h | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index a4e5116..3b0f54b 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -266,5 +266,7 @@ ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
 
 #define atomic_cmpxchg_relaxed(v, o, n) \
 	(cmpxchg_relaxed(&((v)->counter), (o), (n)))
+#define atomic_xchg_relaxed(v, new) \
+	(xchg_relaxed(&((v)->counter), (new)))
 
 #endif /* _ASM_ATOMIC_H */
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
index 620f01a..7830d81 100644
--- a/arch/mips/include/asm/cmpxchg.h
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -110,6 +110,10 @@ unsigned long __xchg(volatile void *ptr, unsigned long x, int size)
 	__res;								\
 })
 
+#define xchg_relaxed(ptr, x)						\
+	((__typeof__(*(ptr)))						\
+		__xchg((ptr), (unsigned long)(x), sizeof(*(ptr))))
+
 #define __cmpxchg_asm(ld, st, m, old, new)				\
 ({									\
 	__typeof(*(m)) __ret;						\
-- 
2.10.2