From patchwork Tue Nov 7 14:06:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13448870 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 4350330F90 for ; Tue, 7 Nov 2023 14:06:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E27FC2 for ; Tue, 7 Nov 2023 06:05:58 -0800 (PST) Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4SPqkT173vz4f3kjT for ; Tue, 7 Nov 2023 22:05:53 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 3556D1A0176 for ; Tue, 7 Nov 2023 22:05:54 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgDHyhA_REpl+VkmAQ--.3051S6; Tue, 07 Nov 2023 22:05:54 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , houtao1@huawei.com Subject: [PATCH bpf 02/11] bpf: Reduce the scope of rcu_read_lock when updating fd map Date: Tue, 7 Nov 2023 22:06:53 +0800 Message-Id: <20231107140702.1891778-3-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20231107140702.1891778-1-houtao@huaweicloud.com> References: <20231107140702.1891778-1-houtao@huaweicloud.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgDHyhA_REpl+VkmAQ--.3051S6 X-Coremail-Antispam: 1UD129KBjvJXoW7Cr4kuF1DGFyDKr1fKrykZrb_yoW8ZFWfp3 95CFy7Kw4Fq3ZF9w1avan29rWUGw15J3yUZFWkJrWrAF17Xrnagr17tas3XFyayFnrArWr Xa4ava9Ykw4UXrDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9Eb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W0oVCq3wA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0 oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7V C0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j 6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28IcxkI7VAKI4 8JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xv wVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjx v20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20E Y4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267 AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU1sa9DUUUUU== X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-Patchwork-Delegate: bpf@iogearbox.net From: Hou Tao There is no rcu-read-lock requirement for ops->map_fd_get_ptr() or ops->map_fd_put_ptr(), so doesn't use rcu-read-lock for these two callbacks. For bpf_fd_array_map_update_elem(), accessing array->ptrs doesn't need rcu-read-lock because array->ptrs will not be freed until the map-in-map is released. For bpf_fd_htab_map_update_elem(), htab_map_update_elem() requires rcu-read-lock to be held, so only use rcu_read_lock() during the invocation of htab_map_update_elem(). Signed-off-by: Hou Tao --- kernel/bpf/hashtab.c | 2 ++ kernel/bpf/syscall.c | 4 ---- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index fd8d4b0addfca..7d1457360c99b 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -2523,7 +2523,9 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, if (IS_ERR(ptr)) return PTR_ERR(ptr); + rcu_read_lock(); ret = htab_map_update_elem(map, key, &ptr, map_flags); + rcu_read_unlock(); if (ret) map->ops->map_fd_put_ptr(ptr); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index a144eb286974b..696b1af8cecbd 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -180,15 +180,11 @@ static int bpf_map_update_value(struct bpf_map *map, struct file *map_file, err = bpf_percpu_cgroup_storage_update(map, key, value, flags); } else if (IS_FD_ARRAY(map)) { - rcu_read_lock(); err = bpf_fd_array_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { - rcu_read_lock(); err = bpf_fd_htab_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) { /* rcu_read_lock() is not needed */ err = bpf_fd_reuseport_array_update_elem(map, key, value,