From 2fd2a6fb7f6935624d327e8bfe25dd3955066429 Mon Sep 17 00:00:00 2001
From: Shaun Tancheff <shaun.tancheff@hpe.com>
Date: Wed, 22 Jun 2022 23:44:47 -0700
Subject: [PATCH] LU-15492 build: fallthrough macro for pre/post gcc-7

gcc-7.5 on openSUSE 15:
   error: this statement may fall through [-Werror=implicit-fallthrough=]

Use the __attribute__((fallthrough)) for gcc-7 and later.
and use a no op statement for earlier gcc where the fallthrough
attribute is not available.

Lustre-change: https://review.whamcloud.com/46357
Lustre-commit: 7b54fc7b1615f23a1ad9da84ba8e289de1f22d70

Test-Parameters: trivial
Fixes: 5549b1b9e0 ("LU-15220 lustre: use 'fallthrough' pseudo keyword for switch")
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: Ib72f5996149c738805f15e354e1e1606d981ce29
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Petros Koutoupis <petros.koutoupis@hpe.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/47708
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---
 lnet/include/lnet/lib-lnet.h      | 6 +++++-
 lustre/include/lustre/lustreapi.h | 6 +++++-
 lustre/include/lustre_compat.h    | 6 +++++-
 lustre/utils/gss/gss_util.h       | 6 +++++-
 4 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/lnet/include/lnet/lib-lnet.h b/lnet/include/lnet/lib-lnet.h
index 11b4330..223c6d3 100644
--- a/lnet/include/lnet/lib-lnet.h
+++ b/lnet/include/lnet/lib-lnet.h
@@ -110,7 +110,11 @@ extern struct lnet the_lnet;			/* THE network */
 #endif
 
 #ifndef fallthrough
-#define fallthrough do {} while (0)  /* fallthrough */
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define fallthrough  __attribute__((fallthrough)) /* fallthrough */
+# else
+#  define fallthrough do {} while (0)  /* fallthrough */
+# endif
 #endif
 
 int choose_ipv4_src(__u32 *ret,
diff --git a/lustre/include/lustre/lustreapi.h b/lustre/include/lustre/lustreapi.h
index 0284da0..4f79fbd 100644
--- a/lustre/include/lustre/lustreapi.h
+++ b/lustre/include/lustre/lustreapi.h
@@ -62,7 +62,11 @@ extern "C" {
 #endif
 
 #ifndef fallthrough
-#define fallthrough do {} while (0)  /* fallthrough */
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define fallthrough  __attribute__((fallthrough)) /* fallthrough */
+# else
+#  define fallthrough do {} while (0)  /* fallthrough */
+# endif
 #endif
 
 typedef struct statx lstatx_t;
diff --git a/lustre/include/lustre_compat.h b/lustre/include/lustre_compat.h
index ccd0960..6338b52 100644
--- a/lustre/include/lustre_compat.h
+++ b/lustre/include/lustre_compat.h
@@ -600,7 +600,11 @@ static inline bool is_root_inode(struct inode *inode)
 #endif
 
 #ifndef fallthrough
-#define fallthrough do {} while (0)  /* fallthrough */
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define fallthrough  __attribute__((fallthrough)) /* fallthrough */
+# else
+#  define fallthrough do {} while (0)  /* fallthrough */
+# endif
 #endif
 
 static inline void ll_security_release_secctx(char *secdata, u32 seclen)
diff --git a/lustre/utils/gss/gss_util.h b/lustre/utils/gss/gss_util.h
index a251fca..07b0f30 100644
--- a/lustre/utils/gss/gss_util.h
+++ b/lustre/utils/gss/gss_util.h
@@ -35,7 +35,11 @@
 #include "write_bytes.h"
 
 #ifndef fallthrough
-#define fallthrough do {} while (0)  /* fallthrough */
+# if defined(__GNUC__) && __GNUC__ >= 7
+#  define fallthrough  __attribute__((fallthrough)) /* fallthrough */
+# else
+#  define fallthrough do {} while (0)  /* fallthrough */
+# endif
 #endif
 
 extern char *this_realm;
-- 
1.8.3.1