Implement getcpu override

[lttng-ust.git] / libringbuffer / getcpu.h

diff --git a/libringbuffer/getcpu.h b/libringbuffer/getcpu.h
index 190eae6c3d39bf131815e57b05c079c772ff103f..fbddb7989336b71235ba238eff9ae860c41a3d6e 100644 (file)
--- a/libringbuffer/getcpu.h
+++ b/libringbuffer/getcpu.h
@@ -20,6 +20,12 @@
  */
 
 #include <urcu/compiler.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+
+void lttng_ust_getcpu_init(void);
+
+extern int (*lttng_get_cpu)(void);
 
 #ifdef LTTNG_UST_DEBUG_VALGRIND
 
@@ -29,7 +35,7 @@
  * migration, so it is only statistically accurate.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
        return 0;
 }
@@ -51,7 +57,7 @@ int lttng_ust_get_cpu(void)
  * If getcpu is not implemented in the kernel, use cpu 0 as fallback.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
        int cpu, ret;
 
@@ -67,7 +73,7 @@ int lttng_ust_get_cpu(void)
  * If getcpu is not implemented in the kernel, use cpu 0 as fallback.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
        int cpu;
 
@@ -85,7 +91,7 @@ int lttng_ust_get_cpu(void)
  * number 0, with the assocated performance degradation on SMP.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
        return 0;
 }
@@ -96,4 +102,16 @@ int lttng_ust_get_cpu(void)
 
 #endif
 
+static inline
+int lttng_ust_get_cpu(void)
+{
+       int (*getcpu)(void) = CMM_LOAD_SHARED(lttng_get_cpu);
+
+       if (caa_likely(!getcpu)) {
+               return lttng_ust_get_cpu_internal();
+       } else {
+               return getcpu();
+       }
+}
+
 #endif /* _LTTNG_GETCPU_H */