netdev - [RFC PATCH bpf-next 0/2] Remove unnecessary synchronizations in cpumap

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Message-Id: <20230728023030.1906124-1-houtao@huaweicloud.com>
Date: Fri, 28 Jul 2023 10:30:28 +0800
From: Hou Tao <houtao@...weicloud.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org,
	"David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Björn Töpel <bjorn.topel@...il.com>,
	Toke Høiland-Jørgensen <toke@...hat.com>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Song Liu <song@...nel.org>,
	Hao Luo <haoluo@...gle.com>,
	Yonghong Song <yonghong.song@...ux.dev>,
	Daniel Borkmann <daniel@...earbox.net>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	houtao1@...wei.com
Subject: [RFC PATCH bpf-next 0/2] Remove unnecessary synchronizations in cpumap

From: Hou Tao <houtao1@...wei.com>

Hi,

The patchset aims to remove unnecessary synchronizations in cpu-map
which were found during code inspection. Patch #1 removes the
unnecessary rcu_barrier() when freeing bpf_cpu_map_entry and replaces
it by queue_rcu_work(). Patch #2 removes the unnecessary call_rcu()
and queue_work() when destroying cpu-map and does the freeing directly.

Simply testing the patchset by running xdp_redirect_cpu test for
virtio-net and no issues are reported. Hope to get more feedback before
removing the RFC tag. As ususal, comments and suggestions are always
welcome.

Regards,
Tao

Hou Tao (2):
  bpf, cpumap: Use queue_rcu_work() to remove unnecessary rcu_barrier()
  bpf, cpumap: Clean up bpf_cpu_map_entry directly in cpu_map_free

 kernel/bpf/cpumap.c | 110 +++++++++++++-------------------------------
 1 file changed, 31 insertions(+), 79 deletions(-)

-- 
2.29.2