linux-kernel - Re: [PATCH] btf: Simplify BTF logic with use of __free(btf

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Message-ID: <20250801111919.13c0620e@gandalf.local.home>
Date: Fri, 1 Aug 2025 11:19:19 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>, Masami
 Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko
 <andrii@...nel.org>, Jiri Olsa <jolsa@...nel.org>, Martin KaFai Lau
 <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, Song Liu
 <song@...nel.org>, KP Singh <kpsingh@...nel.org>
Subject: Re: [PATCH] btf: Simplify BTF logic with use of __free(btf_put)

On Fri, 1 Aug 2025 08:12:08 -0700
Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:

> 
> You can use it in kernel/trace/trace_output.c, of course,

I guess that means I should just use the DEFINE_FREE() in that file
directly and not in the btf.h header file?

> but I really think it's a step back in maintainability.
> All this cleanup.h is not a silver bullet. It needs to be used sparingly.

I have my reservations about the cleanup.h code too. But the more I use it,
the more I like it. My biggest worry is guard() leak. That is, having a
lock or interrupt/preemption disabled for longer than they need to be,
because code was added at the end of the function after the protection is
needed.

-- Steve