[ovs-dev] [PATCH] datapath: compat: Fix static key backport

[Yi-Hung Wei]

The original static key backport is based on the upstream
net-next commit 11276d5306b8
("locking/static_keys: Add a new static_key interface").

However, in Canonical's Trusty kernel, it introduced partial static
support which have different definition of some of the macros that
breaks the compatibility code.

For example, in net-next git tree commit 11276d5306b8
("locking/static_keys: Add a new static_key interface").
+ #define DEFINE_STATIC_KEY_TRUE(name)   \
+       struct static_key_true name = STATIC_KEY_TRUE_INIT

On the other hand, in Canonical's Trusty git tree commit 13f5d5d1cccb6
("x86/KVM/VMX: Add module argument for L1TF mitigation")
+ #define DEFINE_STATIC_KEY_TRUE(name)   \
+       struct static_key name = STATIC_KEY_INIT_TRUE

This commit resolves the ovs kernel module compatibility issue on
Trusty kernel.

VMware-BZ: #2251101
Fixes: 6660a9597a49 ("datapath: compat: Introduce static key support")
Signed-off-by: Yi-Hung Wei <yihung.wei at gmail.com>
---
 acinclude.m4                                     |  4 +++-
 datapath/linux/compat/include/linux/static_key.h | 20 ++++++++++++++------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index ed83df43df54..63da2d38e14e 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -470,8 +470,10 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/err.h], [IS_ERR_OR_NULL])
   OVS_GREP_IFELSE([$KSRC/include/linux/err.h], [PTR_ERR_OR_ZERO])
 
-  OVS_GREP_IFELSE([$KSRC/include/linux/jump_label.h], [DEFINE_STATIC_KEY_FALSE],
+  OVS_GREP_IFELSE([$KSRC/include/linux/jump_label.h], [static_branch_unlikely(],
                   [OVS_DEFINE([HAVE_UPSTREAM_STATIC_KEY])])
+  OVS_GREP_IFELSE([$KSRC/include/linux/jump_label.h], [DEFINE_STATIC_KEY_FALSE],
+                  [OVS_DEFINE([HAVE_DEFINE_STATIC_KEY])])
 
   OVS_GREP_IFELSE([$KSRC/include/linux/etherdevice.h], [eth_hw_addr_random])
   OVS_GREP_IFELSE([$KSRC/include/linux/etherdevice.h], [ether_addr_copy])
diff --git a/datapath/linux/compat/include/linux/static_key.h b/datapath/linux/compat/include/linux/static_key.h
index ea59e3e285a1..01c6a93f07fe 100644
--- a/datapath/linux/compat/include/linux/static_key.h
+++ b/datapath/linux/compat/include/linux/static_key.h
@@ -23,16 +23,16 @@ struct static_key_false {
 #define rpl_STATIC_KEY_INIT_TRUE	{ .enabled = ATOMIC_INIT(1) }
 #define rpl_STATIC_KEY_INIT_FALSE	{ .enabled = ATOMIC_INIT(0) }
 
-#define STATIC_KEY_TRUE_INIT	\
+#define rpl_STATIC_KEY_TRUE_INIT	\
 	(struct static_key_true) { .key = rpl_STATIC_KEY_INIT_TRUE,  }
-#define STATIC_KEY_FALSE_INIT	\
+#define rpl_STATIC_KEY_FALSE_INIT	\
 	(struct static_key_false){ .key = rpl_STATIC_KEY_INIT_FALSE, }
 
-#define DEFINE_STATIC_KEY_TRUE(name)	\
-	struct static_key_true name = STATIC_KEY_TRUE_INIT
+#define rpl_DEFINE_STATIC_KEY_TRUE(name)	\
+	struct static_key_true name = rpl_STATIC_KEY_TRUE_INIT
 
-#define DEFINE_STATIC_KEY_FALSE(name)	\
-	struct static_key_false name = STATIC_KEY_FALSE_INIT
+#define rpl_DEFINE_STATIC_KEY_FALSE(name)	\
+	struct static_key_false name = rpl_STATIC_KEY_FALSE_INIT
 
 static inline int rpl_static_key_count(struct static_key *key)
 {
@@ -59,6 +59,14 @@ static inline void rpl_static_key_disable(struct static_key *key)
 		static_key_slow_dec(key);
 }
 
+#ifdef	HAVE_DEFINE_STATIC_KEY
+#undef	DEFINE_STATIC_KEY_TRUE
+#undef	DEFINE_STATIC_KEY_FALSE
+#endif
+
+#define DEFINE_STATIC_KEY_TRUE		rpl_DEFINE_STATIC_KEY_TRUE
+#define DEFINE_STATIC_KEY_FALSE		rpl_DEFINE_STATIC_KEY_FALSE
+
 #define static_branch_likely(x)		likely(static_key_enabled(&(x)->key))
 #define static_branch_unlikely(x)	unlikely(static_key_enabled(&(x)->key))
 
-- 
2.7.4