From: "Paul E. McKenney" <paulmck@kernel.org>
To: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Song Liu <song@kernel.org>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
bpf@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH bpf] Use call_rcu_hurry() with synchronize_rcu_mult()
Date: Thu, 18 May 2023 07:47:32 -0700 [thread overview]
Message-ID: <358bde93-4933-4305-ac42-4d6f10c97c08@paulmck-laptop> (raw)
The bpf_struct_ops_map_free() function must wait for both an RCU grace
period and an RCU Tasks grace period, and so it passes call_rcu() and
call_rcu_tasks() to synchronize_rcu_mult(). This works, but on ChromeOS
and Android platforms call_rcu() can have lazy semantics, resulting in
multi-second delays between call_rcu() invocation and invocation of the
corresponding callback.
Therefore, substitute call_rcu_hurry() for call_rcu().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: <bpf@vger.kernel.org>
Cc: <netdev@vger.kernel.org>
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index d3f0a4825fa6..bacffd6cae60 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -634,7 +634,7 @@ static void bpf_struct_ops_map_free(struct bpf_map *map)
* in the tramopline image to finish before releasing
* the trampoline image.
*/
- synchronize_rcu_mult(call_rcu, call_rcu_tasks);
+ synchronize_rcu_mult(call_rcu_hurry, call_rcu_tasks);
__bpf_struct_ops_map_free(map);
}
next reply other threads:[~2023-05-18 14:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-18 14:47 Paul E. McKenney [this message]
2023-05-18 16:51 ` [PATCH bpf] Use call_rcu_hurry() with synchronize_rcu_mult() Martin KaFai Lau
2023-05-18 17:25 ` Paul E. McKenney
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