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([2620:10d:c090:500::3:93b1]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b6b34c0f7fsm17960598eec.3.2026.01.20.09.55.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jan 2026 09:55:03 -0800 (PST) Message-ID: <5ca8756f0387e5b2be47e9522b1f4b5fc149768d.camel@gmail.com> Subject: Re: [PATCH bpf RESEND v2 1/2] bpf: Fix memory access flags in helper prototypes From: Eduard Zingerman To: Zesen Liu Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Matt Bobrowski , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Daniel Xu , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, netdev@vger.kernel.org, Shuran Liu , Peili Gao , Haoran Ni Date: Tue, 20 Jan 2026 09:54:59 -0800 In-Reply-To: References: <20260118-helper_proto-v2-0-ab3a1337e755@gmail.com> <20260118-helper_proto-v2-1-ab3a1337e755@gmail.com> <55f01664fc714615206cc8d100cabf4f310f2302.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-01-20 at 11:39 +0800, Zesen Liu wrote: > [...] >=20 > > On Jan 20, 2026, at 04:24, Eduard Zingerman wrote: > >=20 > > Q: why ARG_PTR_TO_UNINIT_MEM here, but not for a previous function and > > not for snprintf variants? >=20 > For bpf_get_stack_proto_raw_tp, I chose ARG_PTR_TO_UNINIT_MEM to be consi= stent with its siblings: >=20 > =E2=80=A2 bpf_get_stack_proto_tp (bpf_trace.c:1425) > =E2=80=A2 bpf_get_stack_proto (stackmap.c:525) > =E2=80=A2 bpf_get_stack_sleepable_proto (stackmap.c:541) >=20 > All of these are wrappers around the same core function bpf_get_stack() /= __bpf_get_stack(), passing the buffer with identical semantics, and all us= e ARG_PTR_TO_UNINIT_MEM. Ack, makes sense, thank you for explaining.