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

From: Rong Tao <rtoax@foxmail.com>
To: olsajiri@gmail.com, andrii@kernel.org, daniel@iogearbox.net,
	sdf@google.com
Cc: Rong Tao <rongtao@cestc.cn>, Alexei Starovoitov <ast@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	bpf@vger.kernel.org (open list:BPF [GENERAL] (Safe Dynamic
	Programs and Tools)), linux-kernel@vger.kernel.org (open list),
	linux-kselftest@vger.kernel.org (open list:KERNEL SELFTEST
	FRAMEWORK),
	linux-stm32@st-md-mailman.stormreply.com (moderated
	list:ARM/STM32 ARCHITECTURE),
	linux-arm-kernel@lists.infradead.org (moderated list:ARM/STM32
	ARCHITECTURE)
Subject: [PATCH bpf-next v11 2/2] selftests/bpf: trace_helpers.c: Add a global ksyms initialization mutex
Date: Tue,  5 Sep 2023 22:04:19 +0800	[thread overview]
Message-ID: <tencent_B44B7295FED7E0D11EC445032021F2AC8107@qq.com> (raw)
In-Reply-To: <cover.1693922135.git.rongtao@cestc.cn>

From: Rong Tao <rongtao@cestc.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@cestc.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 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;
 }
 
-- 
2.41.0

