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Wed, 29 Apr 2020 01:32:41 +0000 Date: Tue, 28 Apr 2020 18:32:39 -0700 From: Martin KaFai Lau To: Yonghong Song CC: Andrii Nakryiko , , , Alexei Starovoitov , Daniel Borkmann , Subject: Re: [PATCH bpf-next v1 06/19] bpf: support bpf tracing/iter programs for BPF_LINK_UPDATE Message-ID: <20200429013239.apxevcpdc3kpqlrq@kafai-mbp> References: <20200427201235.2994549-1-yhs@fb.com> <20200427201241.2995075-1-yhs@fb.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200427201241.2995075-1-yhs@fb.com> User-Agent: NeoMutt/20180716 X-ClientProxiedBy: MWHPR14CA0027.namprd14.prod.outlook.com (2603:10b6:300:12b::13) 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::5:950c) by MWHPR14CA0027.namprd14.prod.outlook.com (2603:10b6:300:12b::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2958.19 via Frontend Transport; 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> int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx); > int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog); > +int bpf_iter_link_replace(struct bpf_link *link, struct bpf_prog *old_prog, > + struct bpf_prog *new_prog); > > 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); > diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c > index 9532e7bcb8e1..fc1ce5ee5c3f 100644 > --- a/kernel/bpf/bpf_iter.c > +++ b/kernel/bpf/bpf_iter.c > @@ -23,6 +23,9 @@ static struct list_head targets; > static struct mutex targets_mutex; > static bool bpf_iter_inited = false; > > +/* protect bpf_iter_link.link->prog upddate */ > +static struct mutex bpf_iter_mutex; > + > int bpf_iter_reg_target(struct bpf_iter_reg *reg_info) > { > struct bpf_iter_target_info *tinfo; > @@ -33,6 +36,7 @@ int bpf_iter_reg_target(struct bpf_iter_reg *reg_info) > if (!bpf_iter_inited) { > INIT_LIST_HEAD(&targets); > mutex_init(&targets_mutex); > + mutex_init(&bpf_iter_mutex); > bpf_iter_inited = true; > } > > @@ -121,3 +125,28 @@ int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) > kfree(link); > return err; > } > + > +int bpf_iter_link_replace(struct bpf_link *link, struct bpf_prog *old_prog, > + struct bpf_prog *new_prog) > +{ > + int ret = 0; > + > + mutex_lock(&bpf_iter_mutex); > + if (old_prog && link->prog != old_prog) { > + ret = -EPERM; > + goto out_unlock; > + } > + > + if (link->prog->type != new_prog->type || > + link->prog->expected_attach_type != new_prog->expected_attach_type || > + strcmp(link->prog->aux->attach_func_name, new_prog->aux->attach_func_name)) { Can attach_btf_id be compared instead of strcmp()? > + ret = -EINVAL; > + goto out_unlock; > + } > + > + link->prog = new_prog; Does the old link->prog need a bpf_prog_put()? > + > +out_unlock: > + mutex_unlock(&bpf_iter_mutex); > + return ret; > +}