[ltt-dev] [UST PATCH] Add getcpu error validation

[david.goulet@polymtl.ca (David Goulet)]

This check is important for the case where getcpu(2) is not
implemented by the Kernel. So, the CPU 0 is the fallback.

Signed-off-by: David Goulet <david.goulet at polymtl.ca>
---
 libust/tracer.h |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/libust/tracer.h b/libust/tracer.h
index 64996b2..dd524af 100644
--- a/libust/tracer.h
+++ b/libust/tracer.h
@@ -345,8 +345,14 @@ static __inline__ void ltt_write_trace_header(struct ust_trace *trace,
 
 static __inline__ int ust_get_cpu(void)
 {
+	int cpu = 0;
 #ifndef UST_VALGRIND
-	return sched_getcpu();
+	if ((cpu = sched_getcpu()) < 0) {
+		/* If getcpu(2) is not implemented in the Kernel
+		 * use CPU 0 as fallback.
+		 */
+		cpu = 0;
+	}
 #else
 	/* Valgrind does not support the sched_getcpu() vsyscall.
 	 * It causes it to detect a segfault in the program and stop it.
@@ -354,7 +360,7 @@ static __inline__ int ust_get_cpu(void)
 	 * from using this call. TODO: it would probably be better to return
 	 * other values too, to better test it.
 	 */
-	return 0;
+	return cpu;
 #endif
 }
 
-- 
1.7.4