From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yonghong Song Subject: [PATCH bpf-next 1/2] bpf: implement syscall command BPF_MAP_GET_NEXT_KEY for stacktrace map Date: Wed, 3 Jan 2018 23:27:45 -0800 Message-ID: <20180104072746.1569033-2-yhs@fb.com> References: <20180104072746.1569033-1-yhs@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: To: , , Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:35006 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbeADH1t (ORCPT ); Thu, 4 Jan 2018 02:27:49 -0500 Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id w047NBZx014602 for ; Wed, 3 Jan 2018 23:27:48 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2f9cub89dj-2 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 03 Jan 2018 23:27:48 -0800 In-Reply-To: <20180104072746.1569033-1-yhs@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: Currently, bpf syscall command BPF_MAP_GET_NEXT_KEY is not supported for stacktrace map. However, there are use cases where user space wants to enumerate all stacktrace map entries where BPF_MAP_GET_NEXT_KEY command will be really helpful. In addition, if user space wants to delete all map entries in order to save memory and does not want to close the map file descriptor, BPF_MAP_GET_NEXT_KEY may help improve performance if map entries are sparsely populated. The implementation follows the API specification of existing BPF_MAP_GET_NEXT_KEY implementation. If user provides an NULL key pointer, the first key is returned. Otherwise, the first valid key after the input parameter "key" is returned, or -ENOENT if no valid key can be found. Signed-off-by: Yonghong Song --- kernel/bpf/stackmap.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index a15bc63..207b21c 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -226,9 +226,28 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) return 0; } -static int stack_map_get_next_key(struct bpf_map *map, void *key, void *next_key) +static int stack_map_get_next_key(struct bpf_map *map, void *key, + void *next_key) { - return -EINVAL; + struct bpf_stack_map *smap = container_of(map, + struct bpf_stack_map, map); + u32 id; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + if (!key) + id = 0; + else + id = *(u32 *)key + 1; + + while (id < smap->n_buckets && !smap->buckets[id]) + id++; + + if (id >= smap->n_buckets) + return -ENOENT; + + *(u32 *)next_key = id; + return 0; } static int stack_map_update_elem(struct bpf_map *map, void *key, void *value, -- 2.9.5