[PATCH stable-4.1.y] tools include: Add a __fallthrough statement

[PATCH stable-4.1.y] tools include: Add a __fallthrough statement

[Florian Fainelli]

From: Arnaldo Carvalho de Melo <acme@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.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: William Cohen <wcohen@redhat.com>
Link: http://lkml.kernel.org/n/tip-qnpig0xfop4hwv6k4mv1wts5@git.kernel.org
Fixes: ed8306908374 ("perf top: Use __fallthrough")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 tools/include/linux/compiler.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 88461f09cc86..8717c80f759c 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -37,4 +37,12 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifndef __fallthrough
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define __fallthrough __attribute__ ((fallthrough))
+# else
+#  define __fallthrough
+# endif
+#endif
+
 #endif /* _TOOLS_LINUX_COMPILER_H */
-- 
2.14.1

Re: [PATCH stable-4.1.y] tools include: Add a __fallthrough statement

[Levin, Alexander (Sasha Levin)]

On Fri, Oct 27, 2017 at 12:05:58PM -0700, Florian Fainelli wrote:
>From: Arnaldo Carvalho de Melo <acme@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.

Queued up, thanks!

-- 

Thanks,
Sasha