[tip:perf/core] tools arch x86: Introduce atomic_cmpxchg()

[tip-bot for Arnaldo Carvalho de Melo <tipbot@zytor.com>]

Commit-ID:  8a73615df3b8973df2de1455c00e9169522d8257
Gitweb:     http://git.kernel.org/tip/8a73615df3b8973df2de1455c00e9169522d8257
Author:     Arnaldo Carvalho de Melo <acme@redhat.com>
AuthorDate: Wed, 22 Feb 2017 16:55:43 -0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 3 Mar 2017 19:07:13 -0300

tools arch x86: Introduce atomic_cmpxchg()

Will be used by atomic_cmpxchg_relaxed(), in turn used by refcount.h.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kdmovd3l4gw5b1w31ypr6ddv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/arch/x86/include/asm/atomic.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/arch/x86/include/asm/atomic.h b/tools/arch/x86/include/asm/atomic.h
index 059e33e..328eece 100644
--- a/tools/arch/x86/include/asm/atomic.h
+++ b/tools/arch/x86/include/asm/atomic.h
@@ -7,6 +7,8 @@
 
 #define LOCK_PREFIX "\n\tlock; "
 
+#include <asm/cmpxchg.h>
+
 /*
  * Atomic operations that C can't guarantee us.  Useful for
  * resource counting etc..
@@ -62,4 +64,9 @@ static inline int atomic_dec_and_test(atomic_t *v)
 	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
 }
 
+static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+	return cmpxchg(&v->counter, old, new);
+}
+
 #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */