linux-kernel - [PATCH bpf-next v10 2/2] selftests/bpf: trace_helpers.c: Add a global ksyms initialization mutex

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Date:   Sat,  2 Sep 2023 13:14:05 +0800
From:   Rong Tao <rtoax@...mail.com>
To:     olsajiri@...il.com, andrii@...nel.org, daniel@...earbox.net,
        sdf@...gle.com
Cc:     Rong Tao <rongtao@...tc.cn>, Alexei Starovoitov <ast@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Hao Luo <haoluo@...gle.com>,
        Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>,
        Shuah Khan <shuah@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Yafang Shao <laoar.shao@...il.com>,
        bpf@...r.kernel.org (open list:BPF [GENERAL] (Safe Dynamic Programs and
        Tools)), linux-kernel@...r.kernel.org (open list),
        linux-kselftest@...r.kernel.org (open list:KERNEL SELFTEST FRAMEWORK),
        linux-stm32@...md-mailman.stormreply.com (moderated list:ARM/STM32
        ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:ARM/STM32
        ARCHITECTURE)
Subject: [PATCH bpf-next v10 2/2] selftests/bpf: trace_helpers.c: Add a global ksyms initialization mutex

From: Rong Tao <rongtao@...tc.cn>

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 <rongtao@...tc.cn>
---
 tools/testing/selftests/bpf/trace_helpers.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index d64c4ef336e1..500b60226e5e 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)
@@ -115,8 +117,10 @@ struct ksyms *load_kallsyms_local(void)
 
 int load_kallsyms(void)
 {
+	pthread_mutex_lock(&ksyms_mutex);
 	if (!ksyms)
 		ksyms = load_kallsyms_local();
+	pthread_mutex_unlock(&ksyms_mutex);
 	return ksyms ? 0 : 1;
 }
 
-- 
2.41.0