4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnaldo Carvalho de Melo <a...@redhat.com>

commit b5bf1733d6a391c4e90ea8f8468d83023be74a2a upstream.

For cases where implicit fall through case labels are intended,
to let us inform that to gcc >= 7:

    CC       /tmp/build/perf/util/string.o
  util/string.c: In function 'perf_atoll':
  util/string.c:22:7: error: this statement may fall through 
[-Werror=implicit-fallthrough=]
      if (*p)
         ^
  util/string.c:24:3: note: here
     case '\0':
     ^~~~

So we introduce:

  #define __fallthrough __attribute__ ((fallthrough))

And use it in such cases.

Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: David Ahern <dsah...@gmail.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Wang Nan <wangn...@huawei.com>
Cc: William Cohen <wco...@redhat.com>
Link: http://lkml.kernel.org/n/tip-qnpig0xfop4hwv6k4mv1w...@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 tools/include/linux/compiler.h |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -115,4 +115,13 @@ static __always_inline void __write_once
 #define WRITE_ONCE(x, val) \
        ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+
+#ifndef __fallthrough
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define __fallthrough __attribute__ ((fallthrough))
+# else
+#  define __fallthrough
+# endif
+#endif
+
 #endif /* _TOOLS_LINUX_COMPILER_H */


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