From patchwork Fri Dec 22 12:21:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philo Lu X-Patchwork-Id: 13503299 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15A5418631; Fri, 22 Dec 2023 12:21:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=lulie@linux.alibaba.com;NM=1;PH=DS;RN=22;SR=0;TI=SMTPD_---0Vz-mQOA_1703247709; Received: from localhost(mailfrom:lulie@linux.alibaba.com fp:SMTPD_---0Vz-mQOA_1703247709) by smtp.aliyun-inc.com; Fri, 22 Dec 2023 20:21:51 +0800 From: Philo Lu To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, xuanzhuo@linux.alibaba.com, dust.li@linux.alibaba.com, alibuda@linux.alibaba.com, guwen@linux.alibaba.com, hengqi@linux.alibaba.com, shung-hsi.yu@suse.com Subject: [PATCH bpf-next 2/3] bpf: implement map_update_elem to init relay file Date: Fri, 22 Dec 2023 20:21:45 +0800 Message-Id: <20231222122146.65519-3-lulie@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20231222122146.65519-1-lulie@linux.alibaba.com> References: <20231222122146.65519-1-lulie@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 map_update_elem is used to create relay files and bind them with the relay channel, which is created with BPF_MAP_CREATE. This allows users to set a custom directory name. It must be used with key=NULL and flag=0. Here is an example: ``` struct { __uint(type, BPF_MAP_TYPE_RELAY); __uint(max_entries, 4096); } my_relay SEC(".maps"); ... char dir_name[] = "relay_test"; bpf_map_update_elem(map_fd, NULL, dir_name, 0); ``` Then, directory `/sys/kerenl/debug/relay_test` will be created, which includes files of my_relay0...my_relay[#cpu]. Each represents a per-cpu buffer with size 8 * 4096 B (there are 8 subbufs by default, each with size 4096B). Signed-off-by: Philo Lu --- kernel/bpf/relaymap.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/relaymap.c b/kernel/bpf/relaymap.c index d0adc7f67758..588c8de0a4bd 100644 --- a/kernel/bpf/relaymap.c +++ b/kernel/bpf/relaymap.c @@ -117,7 +117,37 @@ static void *relay_map_lookup_elem(struct bpf_map *map, void *key) static long relay_map_update_elem(struct bpf_map *map, void *key, void *value, u64 flags) { - return -EOPNOTSUPP; + struct bpf_relay_map *rmap; + struct dentry *parent; + int err; + + if (unlikely(flags)) + return -EINVAL; + + if (unlikely(key)) + return -EINVAL; + + rmap = container_of(map, struct bpf_relay_map, map); + + /* The directory already exists */ + if (rmap->relay_chan->has_base_filename) + return -EEXIST; + + /* Setup relay files. Note that the directory name passed as value should + * not be longer than map->value_size, including the '\0' at the end. + */ + ((char *)value)[map->value_size - 1] = '\0'; + parent = debugfs_create_dir(value, NULL); + if (IS_ERR_OR_NULL(parent)) + return PTR_ERR(parent); + + err = relay_late_setup_files(rmap->relay_chan, map->name, parent); + if (err) { + debugfs_remove_recursive(parent); + return err; + } + + return 0; } static long relay_map_delete_elem(struct bpf_map *map, void *key)