From: "Manuel López-Ibáñez" <lopezibanez@gmail.com>
To: "gcc@gnu.org" <gcc@gnu.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH] panic: suppress gnu_printf warning
Date: Tue, 9 Jan 2024 14:25:00 +0100 [thread overview]
Message-ID: <25d6f0b5-9693-4c16-913e-04c69d317408@gmail.com> (raw)
In-Reply-To: <20240107102103.3c0ba0cfa4df37df4b59090e@linux-foundation.org>
On 07/01/2024 19:21, Andrew Morton wrote:
> On Sun, 7 Jan 2024 17:16:41 +0800 Baoquan He <bhe@redhat.com> wrote:
>
>> with GCC 13.2.1 and W=1, there's compiling warning like this:
>>
>> kernel/panic.c: In function ?__warn?:
>> kernel/panic.c:676:17: warning: function ?__warn? might be a candidate for ?gnu_printf? format attribute [-Wsuggest-attribute=format]
>> 676 | vprintk(args->fmt, args->args);
>> | ^~~~~~~
>>
>> The normal __printf(x,y) adding can't fix it. So add workaround which
>> disables -Wsuggest-attribute=format to mute it.
>>
>> ...
>>
>> --- a/kernel/panic.c
>> +++ b/kernel/panic.c
>> @@ -666,8 +666,13 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
>> pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
>> raw_smp_processor_id(), current->pid, caller);
>>
>> +#pragma GCC diagnostic push
>> +#ifndef __clang__
>> +#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
>> +#endif
>> if (args)
>> vprintk(args->fmt, args->args);
>> +#pragma GCC diagnostic pop
>>
>> print_modules();
> __warn() clearly isn't such a candidate. I'm suspecting that gcc's
> implementation of this warning is pretty crude. Is it a new thing in
> gcc-13.2?
I suspect the warning is about vprintk(), which does seem a printf-like
function but something (early inlining?) may be messing up the context and GCC
warns about __warn(). This may be bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=28492
If vprintk() already has the format attribute, then the messed up function name
may be confusing GCC into warning again about it.
Best wishes,
Manuel.
prev parent reply other threads:[~2024-01-09 13:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240107091641.579849-1-bhe@redhat.com>
2024-01-07 18:21 ` Andrew Morton
2024-01-08 1:56 ` Baoquan He
2024-01-09 13:25 ` Manuel López-Ibáñez [this message]
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