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Thu, 19 Jun 2025 10:57:52 -0700 (PDT) Received: from [192.168.0.56] ([38.34.87.7]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7490a46ace8sm341594b3a.24.2025.06.19.10.57.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Jun 2025 10:57:52 -0700 (PDT) Message-ID: <50c2f252620107b6fa6642e281a91db444b032c5.camel@gmail.com> Subject: Re: [PATCH bpf-next 1/2] bpf: add bpf_dynptr_memset() kfunc From: Eduard Zingerman To: Ihor Solodrai , Mykyta Yatsenko , andrii@kernel.org Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, mykolal@fb.com, kernel-team@meta.com Date: Thu, 19 Jun 2025 10:57:50 -0700 In-Reply-To: <7e7e4056-e2b8-41a5-a6b2-a2fbe0a94f4c@linux.dev> References: <20250618223310.3684760-1-isolodrai@meta.com> <45390c6c-bd2a-4962-8222-1ad346f9908c@linux.dev> <7852f30ba177dc5b811bb0840ca0f301df2a8b58.camel@gmail.com> <7e7e4056-e2b8-41a5-a6b2-a2fbe0a94f4c@linux.dev> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-06-19 at 10:55 -0700, Ihor Solodrai wrote: [...] > > I think Mykyta has kernel/trace/bpf_trace.c:__bpf_dynptr_copy_str() in = mind. >=20 > Thanks for the pointer. So it looks like memset can use > bpf_dynptr_slice_rdwr() to handle xdp/skb cases. Something like: >=20 > void *ptr =3D bpf_dynptr_slice_rdwr(&dynptr, 0, buffer, sizeof(buffe= r)); > if (!ptr) > return -EINVAL; >=20 > memset(ptr, val, n); >=20 > if (ptr =3D=3D buffer) > bpf_dynptr_write(&dynptr, 0, buffer, sizeof(buffer), 0); >=20 >=20 I think so. In a loop.