linux-kernel - [tip:perf/core] tools include: Provide gcc based cmpxchg fallback for !x86

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Date:   Mon, 6 Mar 2017 23:30:48 -0800
From:   tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, acme@...hat.com,
        elena.reshetova@...el.com, hpa@...or.com, dsahern@...il.com,
        wangnan0@...wei.com, tglx@...utronix.de, peterz@...radead.org,
        namhyung@...nel.org, jolsa@...nel.org, mingo@...nel.org,
        adrian.hunter@...el.com
Subject: [tip:perf/core] tools include: Provide gcc based cmpxchg fallback
 for !x86

Commit-ID:  ed4aad50ea0384737034b39f952f29cfb2da52ac
Gitweb:     http://git.kernel.org/tip/ed4aad50ea0384737034b39f952f29cfb2da52ac
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Thu, 23 Feb 2017 15:33:02 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Fri, 3 Mar 2017 19:07:14 -0300

tools include: Provide gcc based cmpxchg fallback for !x86

We've been using an atomic_t implementation subset based on the gcc
builtin functions for a while, now, with refcount.h we need cmpxchg(),
use gcc's __sync_val_compare_and_swap() for that.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Elena Reshetova <elena.reshetova@...el.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-b9zovyxgpa0c4vi3nm0kjo97@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/include/asm-generic/atomic-gcc.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/include/asm-generic/atomic-gcc.h b/tools/include/asm-generic/atomic-gcc.h
index 2ba78c9..5e9738f 100644
--- a/tools/include/asm-generic/atomic-gcc.h
+++ b/tools/include/asm-generic/atomic-gcc.h
@@ -60,4 +60,12 @@ static inline int atomic_dec_and_test(atomic_t *v)
 	return __sync_sub_and_fetch(&v->counter, 1) == 0;
 }
 
+#define cmpxchg(ptr, oldval, newval) \
+	__sync_val_compare_and_swap(ptr, oldval, newval)
+
+static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
+{
+	return cmpxchg(&(v)->counter, oldval, newval);
+}
+
 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */