[bpf-next,v11,2/2] selftests/bpf: trace_helpers.c: Add a global ksyms initialization mutex

Commit Message

Rong Tao Sept. 5, 2023, 2:04 p.m. UTC

From: Rong Tao <[e-mail]>

As Jirka said [0], we just need to make sure that global ksyms
initialization won't race.

[0] https://lore.kernel.org/lkml/ZPCbAs3ItjRd8XVh@krava/

Signed-off-by: Rong Tao <[e-mail]>
---
 tools/testing/selftests/bpf/trace_helpers.c | 4 ++++
 1 file changed, 4 insertions(+)

Patch

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 7d026c128252..411f87d5aac7 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -7,6 +7,7 @@ 
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
+#include <pthread.h>
 #include <unistd.h>
 #include <linux/perf_event.h>
 #include <sys/mman.h>
@@ -26,6 +27,7 @@  struct ksyms {
 };
 
 static struct ksyms *ksyms;
+static pthread_mutex_t ksyms_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 static int ksyms__add_symbol(struct ksyms *ksyms, const char *name,
 			     unsigned long addr)
@@ -110,8 +112,10 @@  struct ksyms *load_kallsyms_local(struct ksyms *ksyms)
 
 int load_kallsyms(void)
 {
+	pthread_mutex_lock(&ksyms_mutex);
 	if (!ksyms)
 		ksyms = load_kallsyms_local(NULL);
+	pthread_mutex_unlock(&ksyms_mutex);
 	return ksyms ? 0 : 1;
 }