linux-kernel - Re: [PATCH] bpf: fix dump

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Message-ID: <4ba5fd7e81438037189a89697b1ba6c8a67f4818.camel@gmail.com>
Date: Tue, 08 Jul 2025 12:07:36 -0700
From: Eduard Zingerman <eddyz87@...il.com>
To: Arnd Bergmann <arnd@...nel.org>, Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko
 <andrii@...nel.org>, Kumar Kartikeya Dwivedi	 <memxor@...il.com>, Emil
 Tsalapatis <emil@...alapatis.com>
Cc: Arnd Bergmann <arnd@...db.de>, Martin KaFai Lau <martin.lau@...ux.dev>, 
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>, John
 Fastabend	 <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev	 <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri
 Olsa <jolsa@...nel.org>, 	bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bpf: fix dump_stack() type cast

On Tue, 2025-07-08 at 18:07 +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> Passing a pointer as a 'u64' variable requires a double cast when
> converting it back to a pointer:
> 
> kernel/bpf/stream.c: In function 'dump_stack_cb':
> kernel/bpf/stream.c:505:64: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>   505 |         ctxp->err = bpf_stream_stage_printk(ctxp->ss, "%pS\n", (void *)ip);
>       |                                                                ^
> 
> Fixes: d7c431cafcb4 ("bpf: Add dump_stack() analogue to print to BPF stderr")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---

This warning is already fixed in
bfa2bb9abd99be ("bpf: Fix improper int-to-ptr cast in dump_stack_cb"),
which landed in bpf-next yesterday.

[...]