linux-kernel - Re: [PATCH v1 1/1] panic: Fix compilation error (`make W=1`)

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Message-ID: <aHBgwRrFfmEWcp-T@U-2FWC9VHC-2323.local>
Date: Fri, 11 Jul 2025 08:54:25 +0800
From: Feng Tang <feng.tang@...ux.alibaba.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Petr Mladek <pmladek@...e.com>
Subject: Re: [PATCH v1 1/1] panic: Fix compilation error (`make W=1`)

On Thu, Jul 10, 2025 at 03:01:33PM -0700, Andrew Morton wrote:
> On Thu, 10 Jul 2025 12:48:16 +0300 Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> 
> > Compiler is not happy about the recently added code:
> > 
> > lib/sys_info.c:52:19: error: variable 'sys_info_avail' is not needed and will not be emitted [-Werror,-Wunneeded-internal-declaration]
> >    52 | static const char sys_info_avail[] = "tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks";
> >       |                   ^~~~~~~~~~~~~~
> > 
> > Fix it in the same way how, for example, lib/vsprintf.c does in the similar
> > cases, i.e. by using string literal directly as sizeof() parameter.
> > 
> > ...
> >
> 
> > --- a/lib/sys_info.c
> > +++ b/lib/sys_info.c
> > @@ -49,13 +49,11 @@ unsigned long sys_info_parse_param(char *str)
> >  
> >  #ifdef CONFIG_SYSCTL
> >  
> > -static const char sys_info_avail[] = "tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks";
> > -
> >  int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> >  					  void *buffer, size_t *lenp,
> >  					  loff_t *ppos)
> >  {
> > -	char names[sizeof(sys_info_avail) + 1];
> > +	char names[sizeof("tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks") + 1];
> >  	struct ctl_table table;
> >  	unsigned long *si_bits_global;
> >  
> 
> Yes, that's neater than the fix we currently have.  I'll grab, thanks.

Hi Andrew, Andy,

sys_info_avail[] has another purpose for being a counterpart of si_names[],
which could be extended in future, so we make it obviously stand-alone. As
for definition of si_names[], we explicitly added comment:  

	/*
	 * When 'si_names' gets updated,  please make sure the 'sys_info_avail'
	 * below is updated accordingly.
	 */
	static const struct sys_info_name  si_names[] = {
		{ SYS_INFO_TASKS,		"tasks" },
		{ SYS_INFO_MEM,			"mem" },
		
which has also been discussed in another thread:
https://lore.kernel.org/lkml/aG3o2RFHc5iXnJef@U-2FWC9VHC-2323.local/

And I suggest to keep sys_info_avail[], and either Nathan or Sergey's patch
works for me.

Sorry for the inconvenience, and I should upgrade my gcc :) 

Thanks,
Feng