X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libust%2Ftracer.h;h=2f489f6c7df314a94fdb9208264caec8b57ce6b9;hb=1d471d9fd21c9ef20cd7b0ea54a71168f0ad1b6e;hp=64996b2d61c392ef40e768fbbbf1473797a154db;hpb=205f7ca77a36f7942a3348e7b8ea3c1f86f1c7ee;p=ust.git

diff --git a/libust/tracer.h b/libust/tracer.h
index 64996b2..2f489f6 100644
--- a/libust/tracer.h
+++ b/libust/tracer.h
@@ -343,21 +343,36 @@ static __inline__ void ltt_write_trace_header(struct ust_trace *trace,
 	header->freq_scale = trace->freq_scale;
 }
 
+#ifndef UST_VALGRIND
+
 static __inline__ int ust_get_cpu(void)
 {
-#ifndef UST_VALGRIND
-	return sched_getcpu();
-#else
-	/* Valgrind does not support the sched_getcpu() vsyscall.
+	int cpu;
+
+	cpu = sched_getcpu();
+	if (likely(cpu >= 0))
+		return cpu;
+	/*
+	 * If getcpu(2) is not implemented in the Kernel use CPU 0 as fallback.
+	 */
+	return 0;
+}
+
+#else	/* #else #ifndef UST_VALGRIND */
+
+static __inline__ int ust_get_cpu(void)
+{
+	/*
+	 * Valgrind does not support the sched_getcpu() vsyscall.
 	 * It causes it to detect a segfault in the program and stop it.
 	 * So if we want to check libust with valgrind, we have to refrain
 	 * from using this call. TODO: it would probably be better to return
 	 * other values too, to better test it.
 	 */
 	return 0;
-#endif
 }
 
+#endif	/* #else #ifndef UST_VALGRIND */
 
 /*
  * Size reserved for high priority events (interrupts, NMI, BH) at the end of a