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Tue, 28 Apr 2020 16:20:30 +0000 Date: Tue, 28 Apr 2020 09:20:24 -0700 From: Martin KaFai Lau To: Yonghong Song CC: Andrii Nakryiko , , , Alexei Starovoitov , Daniel Borkmann , Subject: Re: [PATCH bpf-next v1 02/19] bpf: implement an interface to register bpf_iter targets Message-ID: <20200428162024.72iaga3a63hizctg@kafai-mbp> References: <20200427201235.2994549-1-yhs@fb.com> <20200427201236.2994722-1-yhs@fb.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200427201236.2994722-1-yhs@fb.com> User-Agent: NeoMutt/20180716 X-ClientProxiedBy: MWHPR12CA0050.namprd12.prod.outlook.com (2603:10b6:300:103::12) To MW3PR15MB4044.namprd15.prod.outlook.com (2603:10b6:303:4b::24) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from kafai-mbp (2620:10d:c090:400::5:c5c5) by MWHPR12CA0050.namprd12.prod.outlook.com (2603:10b6:300:103::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2937.13 via Frontend Transport; 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When bpf_iter tries to > reuse the same seq_ops, its seq_file private data need the net namespace > setup properly too. In this case, the bpf_iter infrastructure can help > set up properly before doing seq_file operations. > > Signed-off-by: Yonghong Song > --- > include/linux/bpf.h | 11 ++++++++++ > kernel/bpf/Makefile | 2 +- > kernel/bpf/bpf_iter.c | 50 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 62 insertions(+), 1 deletion(-) > create mode 100644 kernel/bpf/bpf_iter.c > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 10960cfabea4..5e56abc1e2f1 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -31,6 +31,7 @@ struct seq_file; > struct btf; > struct btf_type; > struct exception_table_entry; > +struct seq_operations; > > extern struct idr btf_idr; > extern spinlock_t btf_idr_lock; > @@ -1109,6 +1110,16 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd); > int bpf_obj_pin_user(u32 ufd, const char __user *pathname); > int bpf_obj_get_user(const char __user *pathname, int flags); > > +struct bpf_iter_reg { > + const char *target; > + const char *target_func_name; > + const struct seq_operations *seq_ops; > + u32 seq_priv_size; > + u32 target_feature; > +}; > + > +int bpf_iter_reg_target(struct bpf_iter_reg *reg_info); > + > int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value); > int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value); > int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value, > diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile > index f2d7be596966..6a8b0febd3f6 100644 > --- a/kernel/bpf/Makefile > +++ b/kernel/bpf/Makefile > @@ -2,7 +2,7 @@ > obj-y := core.o > CFLAGS_core.o += $(call cc-disable-warning, override-init) > > -obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o > +obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o > obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o > obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o > obj-$(CONFIG_BPF_SYSCALL) += disasm.o > diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c > new file mode 100644 > index 000000000000..1115b978607a > --- /dev/null > +++ b/kernel/bpf/bpf_iter.c > @@ -0,0 +1,50 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* Copyright (c) 2020 Facebook */ > + > +#include > +#include > +#include > + > +struct bpf_iter_target_info { > + struct list_head list; > + const char *target; > + const char *target_func_name; > + const struct seq_operations *seq_ops; > + u32 seq_priv_size; > + u32 target_feature; > +}; > + > +static struct list_head targets; > +static struct mutex targets_mutex; > +static bool bpf_iter_inited = false; The "!bpf_iter_inited" test below is racy. LIST_HEAD_INIT and DEFINE_MUTEX can be used instead. > + > +int bpf_iter_reg_target(struct bpf_iter_reg *reg_info) > +{ > + struct bpf_iter_target_info *tinfo; > + > + /* The earliest bpf_iter_reg_target() is called at init time > + * where the bpf_iter registration is serialized. > + */ > + if (!bpf_iter_inited) { > + INIT_LIST_HEAD(&targets); > + mutex_init(&targets_mutex); > + bpf_iter_inited = true; > + }