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Fri, 20 Mar 2026 05:40:52 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Fri, 20 Mar 2026 13:40:51 +0100 To: Menglong Dong Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, shuah@kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next] selftests/bpf: test access to ringbuf position with map pointer Message-ID: References: <20260320084155.288417-1-dongml2@chinatelecom.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260320084155.288417-1-dongml2@chinatelecom.cn> On Fri, Mar 20, 2026 at 04:41:55PM +0800, Menglong Dong wrote: > Add the testing to access the bpf_ringbuf with the map pointer. > "consumer_pos" and "producer_pos" is accessed in this testing. We reserve > 128 bytes in the ringbuf to test the producer_pos, which should be > "128 + 8", and the "8" is BPF_RINGBUF_HDR_SZ. > > It will be helpful if we want to evaluate the usage of the ringbuf in bpf > prog with the consumer and producer position. > > Signed-off-by: Menglong Dong > --- > .../testing/selftests/bpf/progs/map_ptr_kern.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c b/tools/testing/selftests/bpf/progs/map_ptr_kern.c > index efaf622c28dd..c3fa57ec430b 100644 > --- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c > +++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c > @@ -647,21 +647,39 @@ static inline int check_devmap_hash(void) > return 1; > } > > +struct bpf_ringbuf { > + unsigned long consumer_pos; > + unsigned long producer_pos; > +} __attribute__((preserve_access_index)); > + > struct bpf_ringbuf_map { > struct bpf_map map; > + struct bpf_ringbuf *rb; > } __attribute__((preserve_access_index)); > > struct { > __uint(type, BPF_MAP_TYPE_RINGBUF); > + __uint(max_entries, 1 << 10); do you need to set max_entries? there's already check below making sure it's 4096 jirka > } m_ringbuf SEC(".maps"); > > static inline int check_ringbuf(void) > { > struct bpf_ringbuf_map *ringbuf = (struct bpf_ringbuf_map *)&m_ringbuf; > struct bpf_map *map = (struct bpf_map *)&m_ringbuf; > + struct bpf_ringbuf *rb; > + void *ptr; > > VERIFY(check(&ringbuf->map, map, 0, 0, page_size)); > > + ptr = bpf_ringbuf_reserve(&m_ringbuf, 128, 0); > + VERIFY(ptr); > + > + bpf_ringbuf_discard(ptr, 0); > + rb = ringbuf->rb; > + VERIFY(rb); > + VERIFY(rb->consumer_pos == 0); > + VERIFY(rb->producer_pos == 128 + 8); > + > return 1; > } > > -- > 2.53.0 >