From: Andrew Morton <akpm@linux-foundation.org>
To: Baoquan He <bhe@redhat.com>
Cc: linux-kernel@vger.kernel.org, pmladek@suse.com, gcc@gcc.gnu.org
Subject: Re: [PATCH] panic: suppress gnu_printf warning
Date: Sun, 7 Jan 2024 10:21:03 -0800 [thread overview]
Message-ID: <20240107102103.3c0ba0cfa4df37df4b59090e@linux-foundation.org> (raw)
In-Reply-To: <20240107091641.579849-1-bhe@redhat.com>
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?
A bit of context for gcc@gcc.gnu.org:
struct warn_args {
const char *fmt;
va_list args;
};
...
void __warn(const char *file, int line, void *caller, unsigned taint,
struct pt_regs *regs, struct warn_args *args)
{
disable_trace_on_warning();
if (file)
pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
raw_smp_processor_id(), current->pid, file, line,
caller);
else
pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
raw_smp_processor_id(), current->pid, caller);
if (args)
vprintk(args->fmt, args->args);
print_modules();
if (regs)
show_regs(regs);
check_panic_on_warn("kernel");
if (!regs)
dump_stack();
print_irqtrace_events(current);
print_oops_end_marker();
trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller);
/* Just a warning, don't kill lockdep. */
add_taint(taint, LOCKDEP_STILL_OK);
}
next parent reply other threads:[~2024-01-07 18:21 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 [this message]
2024-01-08 1:56 ` Baoquan He
2024-01-09 13:25 ` Manuel López-Ibáñez
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