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From: Peter Zijlstra <peterz@infradead.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Sam Ravnborg <sam@ravnborg.org>, X86 ML <x86@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Changbin Du <changbin.du@gmail.com>,
	linux-toolchains@vger.kernel.org,
	clang-built-linux <llvm@lists.linux.dev>
Subject: Re: [PATCH] kbuild: Remove CONFIG_DEBUG_SECTION_MISMATCH
Date: Fri, 8 Apr 2022 22:48:05 +0200	[thread overview]
Message-ID: <YlCfhUkOXTvqCfjT@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YlCb3L7ByWwszbaA@hirez.programming.kicks-ass.net>

On Fri, Apr 08, 2022 at 10:32:28PM +0200, Peter Zijlstra wrote:

> > > This weird option is having us upgrade quite a few 'inline' to
> > > '__always_inline'.
> > 
> > As is, the assumption that __init functions only call other __init
> > functions or __always_inline is a brittle house of cards that leads to
> > a "what color is your function" [0] scenario, and leads to code that
> > happens to not emit warnings for compiler X (or compiler X version Y).
> > There's also curious exceptions in modpost that look like memory leaks
> > to me.

So I don't see __always_inline that way (also I'm in the 'inline' should
be '__always_inline' camp).

To me inline is more like: 'instantiate that pattern *here*'. It's like
CPP macros, only less horrible. You get the code generated according to
the local rules (instrumentation yes/no, section, and whatever other
function attributes we have that affect code-gen).

So with inline we can get the same pattern instantiated a number of
different times, leading to different actual code, without having to
type the whole thing multiple times (which would be terrible for
maintenance) etc..

Combine __always_inline with constant propagation of inline function
'pointers' and you get do beautiful things ;-) /me runs

      reply	other threads:[~2022-04-08 20:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <7fad83ecde03540e65677959034315f8fbb3755e.1649434832.git.jpoimboe@redhat.com>
     [not found] ` <CAK7LNARvFcQgEB1b0L6giwx0vD7wU9L-OZ5jvm1c5+StLjeOYQ@mail.gmail.com>
     [not found]   ` <YlCJm8iQBPSOWIT5@hirez.programming.kicks-ass.net>
2022-04-08 20:08     ` [PATCH] kbuild: Remove CONFIG_DEBUG_SECTION_MISMATCH Nick Desaulniers
2022-04-08 20:16       ` Nick Desaulniers
2022-04-08 20:32       ` Peter Zijlstra
2022-04-08 20:48         ` Peter Zijlstra [this message]

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