[PATCH] SMP alternatives: skip with UP kernels

Hide the magic in alternative.h and provide some dummy inline functions
for the UP case (gcc should manage to optimize away these calls).  No
changes in module.c.

Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 23 insertions, 0 deletions

diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 50eb0e03777e..7b421b3a053e 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -168,6 +168,8 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
         }
 }
 
+#ifdef CONFIG_SMP
+
 static void alternatives_smp_save(struct alt_instr *start, struct alt_instr *end)
 {
         struct alt_instr *a;
@@ -328,6 +330,8 @@ void alternatives_smp_switch(int smp)
         spin_unlock_irqrestore(&smp_alt, flags);
 }
 
+#endif
+
 void __init alternative_instructions(void)
 {
         if (no_replacement) {
@@ -349,6 +353,7 @@ void __init alternative_instructions(void)
         smp_alt_once = 1;
 #endif
 
+#ifdef CONFIG_SMP
         if (smp_alt_once) {
                 if (1 == num_possible_cpus()) {
                         printk(KERN_INFO "SMP alternatives: switching to UP code\n");
@@ -370,4 +375,5 @@ void __init alternative_instructions(void)
                                             _text, _etext);
                 alternatives_smp_switch(0);
         }
+#endif
 }
diff --git a/include/asm-i386/alternative.h b/include/asm-i386/alternative.h
index c61bd1a17f37..96adbabec740 100644
--- a/include/asm-i386/alternative.h
+++ b/include/asm-i386/alternative.h
@@ -19,11 +19,19 @@ struct alt_instr {
 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
 
 struct module;
+#ifdef CONFIG_SMP
 extern void alternatives_smp_module_add(struct module *mod, char *name,
                                         void *locks, void *locks_end,
                                         void *text, void *text_end);
 extern void alternatives_smp_module_del(struct module *mod);
 extern void alternatives_smp_switch(int smp);
+#else
+static inline void alternatives_smp_module_add(struct module *mod, char *name,
+                                        void *locks, void *locks_end,
+                                        void *text, void *text_end) {}
+static inline void alternatives_smp_module_del(struct module *mod) {}
+static inline void alternatives_smp_switch(int smp) {}
+#endif
 
 #endif
 
diff --git a/include/asm-x86_64/alternative.h b/include/asm-x86_64/alternative.h
index 387c8f66af7d..aa67bfd1b3ce 100644
--- a/include/asm-x86_64/alternative.h
+++ b/include/asm-x86_64/alternative.h
@@ -17,11 +17,20 @@ struct alt_instr {
 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
 
 struct module;
+
+#ifdef CONFIG_SMP
 extern void alternatives_smp_module_add(struct module *mod, char *name,
                                         void *locks, void *locks_end,
                                         void *text, void *text_end);
 extern void alternatives_smp_module_del(struct module *mod);
 extern void alternatives_smp_switch(int smp);
+#else
+static inline void alternatives_smp_module_add(struct module *mod, char *name,
+                                        void *locks, void *locks_end,
+                                        void *text, void *text_end) {}
+static inline void alternatives_smp_module_del(struct module *mod) {}
+static inline void alternatives_smp_switch(int smp) {}
+#endif
 
 #endif