Move to kernel style SPDX license identifiers

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

diff --git a/libringbuffer/getcpu.h b/libringbuffer/getcpu.h
index 190eae6c3d39bf131815e57b05c079c772ff103f..bb815e66141171aa4af62595dcec4a9d66184d4c 100644 (file)
--- a/libringbuffer/getcpu.h
+++ b/libringbuffer/getcpu.h
@@ -1,25 +1,19 @@
-#ifndef _LTTNG_GETCPU_H
-#define _LTTNG_GETCPU_H
-
 /*
- * Copyright (c) 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
+#ifndef _LTTNG_GETCPU_H
+#define _LTTNG_GETCPU_H
+
 #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 +23,7 @@
  * 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 +35,30 @@ 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 +67,7 @@ int lttng_ust_get_cpu(void)
                return 0;
        return cpu;
 }
-#endif /* __UCLIBC__ */
+#endif /* HAVE_SCHED_GETCPU */
 
 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 
@@ -85,7 +76,7 @@ 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 +87,16 @@ 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 */