linux-kernel - Re: [PATCH bpf-next v6 1/2] bpf: refactor max_depth computation in bpf_get

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Message-ID: <CAADnVQLf0wj9hV=tAA=p_GXgpQ6DxtB4heoDqTmb5dEc5P6zfg@mail.gmail.com>
Date: Wed, 3 Sep 2025 09:12:58 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Arnaud Lecomte <contact@...aud-lcm.com>
Cc: Yonghong Song <yonghong.song@...ux.dev>, Song Liu <song@...nel.org>, 
	Andrii Nakryiko <andrii@...nel.org>, Alexei Starovoitov <ast@...nel.org>, bpf <bpf@...r.kernel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Eduard <eddyz87@...il.com>, Hao Luo <haoluo@...gle.com>, 
	John Fastabend <john.fastabend@...il.com>, Jiri Olsa <jolsa@...nel.org>, 
	KP Singh <kpsingh@...nel.org>, LKML <linux-kernel@...r.kernel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Stanislav Fomichev <sdf@...ichev.me>, 
	syzbot+c9b724fbb41cf2538b7b@...kaller.appspotmail.com, 
	syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: [PATCH bpf-next v6 1/2] bpf: refactor max_depth computation in bpf_get_stack()

On Wed, Sep 3, 2025 at 6:52 AM Arnaud Lecomte <contact@...aud-lcm.com> wrote:
>
> A new helper function stack_map_calculate_max_depth() that
> computes the max depth for a stackmap.
>
> Changes in v2:
>  - Removed the checking 'map_size % map_elem_size' from
>    stack_map_calculate_max_depth
>  - Changed stack_map_calculate_max_depth params name to be more generic
>
> Changes in v3:
>  - Changed map size param to size in max depth helper
>
> Changes in v4:
>  - Fixed indentation in max depth helper for args
>
> Changes in v5:
>  - Bound back trace_nr to num_elem in __bpf_get_stack
>  - Make a copy of sysctl_perf_event_max_stack
>    in stack_map_calculate_max_depth
>
> Changes in v6:
>  - Restrained max_depth computation only when required
>  - Additional cleanup from Song in __bpf_get_stack

This is not a refactor anymore.
Pls don't squash different things into one patch.
Keep refactor as patch 1, and another cleanup as patch 2.

pw-bot: cr