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[195.134.167.217]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4995919df87sm90789365e9.6.2026.08.07.03.11.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Aug 2026 03:11:08 -0700 (PDT) Date: Fri, 7 Aug 2026 12:11:07 +0200 From: Mahe Tardy To: Jiayuan Chen Cc: bpf@vger.kernel.org, andrew+netdev@lunn.ch, andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, eddyz87@gmail.com, edumazet@google.com, john.fastabend@gmail.com, kuba@kernel.org, liamwisehart@meta.com, martin.lau@linux.dev, pabeni@redhat.com, song@kernel.org, netdev@vger.kernel.org, sdf.kernel@gmail.com, ameryhung@gmail.com, kuniyu@google.com, memxor@gmail.com Subject: Re: [PATCH bpf-next v4 3/5] selftests/bpf: Add ksock kfunc test Message-ID: References: <20260806182234.380833-1-mahe.tardy@gmail.com> <20260806182234.380833-4-mahe.tardy@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Aug 07, 2026 at 05:12:21PM +0800, Jiayuan Chen wrote: > > On 8/7/26 2:22 AM, Mahe Tardy wrote: > > Add > [...] > > + > > +SEC("lsm.s/socket_bind") > > +int BPF_PROG(ksock_socket_bind, struct socket *sock, struct sockaddr *address, > > + int addrlen, int ret) > > +{ > > + struct __ksock_ctx_value *v; > > + struct bpf_ksock *ks, *tmp; > > + u32 pid = bpf_get_current_pid_tgid() >> 32; > > + > > + if (ret || pid != target_pid) > > + return ret; > > + > > + v = ksock_ctx_value_lookup(); > > + if (!v) { > > + send_ret = -ENOENT; > > + return ret; > > + } > > + > > + ks = NULL; > > + bpf_rcu_read_lock(); > > + tmp = v->ctx; > > + if (tmp) > > + ks = bpf_ksock_acquire(tmp); > > + bpf_rcu_read_unlock(); > > + > > + if (!ks) { > > + send_ret = -ENOENT; > > + return ret; > > + } > > + > > > Since bpf_ksock_send() is sleepable, every consumer of the kptr is > necessarily a sleepable program and thus has to open-code the same > bpf_rcu_read_lock()/acquire/unlock sequence before each send. > > Given ksock_common.h already wraps the insert side, how about also > providing the get side, e.g.: > > static inline struct bpf_ksock *ksock_ctx_get(void) > { >     struct __ksock_ctx_value *v = ksock_ctx_value_lookup(); >     struct bpf_ksock *ks = NULL, *tmp; > >     if (!v) >             return NULL; >     bpf_rcu_read_lock(); >     tmp = v->ctx; >     if (tmp) >             ks = bpf_ksock_acquire(tmp); >     bpf_rcu_read_unlock(); >     return ks; > } > > These selftests will be the reference everyone copies from, so > encapsulating the RCU dance here also documents the correct usage. > Yeah good idea, I'll just keep a slightly difference dance using bpf_kptr_xchg() in the ksock_lsm_verifier.c program because I want the verifier to bump against bpf_ksock_send() restriction explicitely and not bpf_ksock_acquire().