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authorJoe Perches <joe@perches.com>2019-10-05 09:46:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-10-11 09:26:05 -0700
commit294f69e662d1570703e9b56e95be37a9fd3afba5 (patch)
tree8138e829d29b3f06e3bc1de49cab4a34e31dc1a7
parent48f9bcf91461b43249949f4e172b5c0245dde751 (diff)
downloadlinux-stericsson-294f69e662d1570703e9b56e95be37a9fd3afba5.tar.gz
compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use
Reserve the pseudo keyword 'fallthrough' for the ability to convert the various case block /* fallthrough */ style comments to appear to be an actual reserved word with the same gcc case block missing fallthrough warning capability. All switch/case blocks now should end in one of: break; fallthrough; goto <label>; return [expression]; continue; In C mode, GCC supports the __fallthrough__ attribute since 7.1, the same time the warning and the comment parsing were introduced. fallthrough devolves to an empty "do {} while (0)" if the compiler version (any version less than gcc 7) does not support the attribute. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Suggested-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/compiler_attributes.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 6b318efd8a74..cdf016596659 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -40,6 +40,7 @@
# define __GCC4_has_attribute___noclone__ 1
# define __GCC4_has_attribute___nonstring__ 0
# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
+# define __GCC4_has_attribute___fallthrough__ 0
#endif
/*
@@ -186,6 +187,22 @@
#endif
/*
+ * Add the pseudo keyword 'fallthrough' so case statement blocks
+ * must end with any of these keywords:
+ * break;
+ * fallthrough;
+ * goto <label>;
+ * return [expression];
+ *
+ * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
+ */
+#if __has_attribute(__fallthrough__)
+# define fallthrough __attribute__((__fallthrough__))
+#else
+# define fallthrough do {} while (0) /* fallthrough */
+#endif
+
+/*
* Note the missing underscores.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute