X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Fgetcpu.h;h=7b009dc6cf38efefd67aece71a8308a66a351efb;hb=75026e9f596aa057bd3499a7be43a7fc8aa0b783;hp=190eae6c3d39bf131815e57b05c079c772ff103f;hpb=4327cb7d2c9f34fc8d01f8ed92e2a43de7ef14f6;p=lttng-ust.git

diff --git a/libringbuffer/getcpu.h b/libringbuffer/getcpu.h
index 190eae6c..7b009dc6 100644
--- a/libringbuffer/getcpu.h
+++ b/libringbuffer/getcpu.h
@@ -20,6 +20,13 @@
  */
 
 #include <urcu/compiler.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+#include <config.h>
+
+void lttng_ust_getcpu_init(void);
+
+extern int (*lttng_get_cpu)(void);
 
 #ifdef LTTNG_UST_DEBUG_VALGRIND
 
@@ -29,7 +36,7 @@
  * migration, so it is only statistically accurate.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
 	return 0;
 }
@@ -41,33 +48,30 @@ int lttng_ust_get_cpu(void)
  */
 #ifdef __linux__
 
-/* old uClibc versions didn't have sched_getcpu */
-#if defined(__UCLIBC__) && __UCLIBC_MAJOR__ == 0 && \
-	(__UCLIBC_MINOR__ < 9 || \
-	 (__UCLIBC_MINOR__ == 9 && __UCLIBC_SUBLEVEL__ <= 32))
+#if !HAVE_SCHED_GETCPU
 #include <sys/syscall.h>
 #define __getcpu(cpu, node, cache)	syscall(__NR_getcpu, cpu, node, cache)
 /*
  * 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;
 
 	ret = __getcpu(&cpu, NULL, NULL);
 	if (caa_unlikely(ret < 0))
 		return 0;
-	return c;
+	return cpu;
 }
-#else /* __UCLIBC__ */
+#else /* HAVE_SCHED_GETCPU */
 #include <sched.h>
 
 /*
  * 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;
 
@@ -76,7 +80,7 @@ int lttng_ust_get_cpu(void)
 		return 0;
 	return cpu;
 }
-#endif	/* __UCLIBC__ */
+#endif	/* HAVE_SCHED_GETCPU */
 
 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 
@@ -85,7 +89,7 @@ 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 +100,16 @@ 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 */