From: Steven Rostedt <rostedt@goodmis.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Tom Zanussi <zanussi@kernel.org>
Subject: Re: [GIT PULL] tracing: Updates for 5.10
Date: Thu, 15 Oct 2020 22:21:39 -0400 [thread overview]
Message-ID: <20201015222139.1b92a3be@gandalf.local.home> (raw)
In-Reply-To: <CAHk-=wjU86UhovK4XuwvCqTOfc+nvtpAuaN2PJBz15z=w=u0Xg@mail.gmail.com>
On Thu, 15 Oct 2020 18:54:34 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > Updates for tracing and bootconfig:
>
> Hmm. I haven't verified that this came from you, but it seems likely..
> Once again my clang build shows something that I don't see in my
> allmodconfig gcc build:
>
> WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in
> reference from the function __trace_early_add_events() to the function
> .init.text:__trace_early_add_new_event()
> The function __trace_early_add_events() references
> the function __init __trace_early_add_new_event().
> This is often because __trace_early_add_events lacks a __init
> annotation or the annotation of __trace_early_add_new_event is wrong.
>
> Hmm?
>
> Linus
I see the issue, and I wonder if it has to do with optimization, for gcc
not to warn.
The issue is that we have:
trace_array_create() that can be called at any time. And it has:
if (trace_instance_dir) {
ret = trace_array_create_dir(tr);
if (ret)
goto out_free_tr;
} else
__trace_early_add_events(tr);
Where trace_instance_dir gets set at boot up, and thus the else statement
will never get called after that.
The __trace_early_add_events() then calls __trace_early_add_new_events()
which is __init.
I don't know how gcc didn't trigger this and clang does.
I'll have to think about how to untangle this. Is there some kind of
annotation that makes it show that a path can only be called at boot up and
not later?
-- Steve
next prev parent reply other threads:[~2020-10-16 2:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 17:53 [GIT PULL] tracing: Updates for 5.10 Steven Rostedt
2020-10-15 23:08 ` pr-tracker-bot
2020-10-16 1:54 ` Linus Torvalds
2020-10-16 2:21 ` Steven Rostedt [this message]
2020-10-16 2:53 ` Masami Hiramatsu
2020-10-16 3:54 ` Steven Rostedt
2020-10-16 4:05 ` Masami Hiramatsu
2020-10-16 4:20 ` [PATCH] tracing: Remove __init from __trace_early_add_new_event() Masami Hiramatsu
2020-10-16 2:34 ` [GIT PULL] tracing: Updates for 5.10 Masami Hiramatsu
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