linux-kernel - Re: [PATCH v10 03/14] unwind_user: Add compat mode frame pointer support

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Message-ID: <CAHk-=whGWM50Qq3Dgha8ByU7t_dqvrCk3JFBSw2+X0KUAWuT1g@mail.gmail.com>
Date: Wed, 18 Jun 2025 10:52:22 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org, bpf@...r.kernel.org, x86@...nel.org, 
	Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
	Namhyung Kim <namhyung@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Andrii Nakryiko <andrii@...nel.org>, Indu Bhagat <indu.bhagat@...cle.com>, 
	"Jose E. Marchesi" <jemarch@....org>, Beau Belgrave <beaub@...ux.microsoft.com>, 
	Jens Remus <jremus@...ux.ibm.com>, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v10 03/14] unwind_user: Add compat mode frame pointer support

On Wed, 18 Jun 2025 at 08:10, Steven Rostedt <rostedt@...dmis.org> wrote:
>
> Don't we usually shout macros?

Not really. It's more about "we shout about macros when they _behave_
like macros".

So typically we do all upper-case for things that are constants
(whether enums or macros, actually) or when they don't act like normal
functions.

But when it's not particularly important that it's a macro, and it
could have been a function (but maybe it was just simpler to use a
macro for whatever reason), we typically don't use all upper-case.

In this case, I have to agree with PeterZ that this just looks odd:

-       if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
+       if (UNWIND_GET_USER_LONG(ra, cfa + frame->ra_off, state))

why is UNWIND_GET_USER_LONG() so loud when it just replaces "get_user()"?

Note that "get_user()" itself is a macro, and is lower-case, even
though you couldn't actually do it as a function (because it changes
its first argument in place).

             Linus