linux-kernel - Re: [PATCH] tracing: remove __printf() attribute on __ftrace

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Message-ID: <202602032036.FQK7gJvV-lkp@intel.com>
Date: Tue, 3 Feb 2026 20:12:57 +0800
From: kernel test robot <lkp@...el.com>
To: Arnd Bergmann <arnd@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Simon Horman <horms@...nel.org>, Jeff Layton <jlayton@...nel.org>,
	Anna Schumaker <anna.schumaker@...cle.com>,
	Chuck Lever <chuck.lever@...cle.com>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
	Arnd Bergmann <arnd@...db.de>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yury Norov <ynorov@...dia.com>,
	Joel Fernandes <joelagnelf@...dia.com>,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: remove __printf() attribute on
 __ftrace_vbprintk()

Hi Arnd,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20260130]
[cannot apply to trace/for-next linus/master v6.19-rc8 v6.19-rc7 v6.19-rc6 v6.19-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Arnd-Bergmann/tracing-remove-__printf-attribute-on-__ftrace_vbprintk/20260202-180958
base:   next-20260130
patch link:    https://lore.kernel.org/r/20260202095834.1328352-1-arnd%40kernel.org
patch subject: [PATCH] tracing: remove __printf() attribute on __ftrace_vbprintk()
config: riscv-allmodconfig (https://download.01.org/0day-ci/archive/20260203/202602032036.FQK7gJvV-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260203/202602032036.FQK7gJvV-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602032036.FQK7gJvV-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/trace/trace_printk.c:212:34: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 3)' attribute to the declaration of '__trace_bprintk' [-Wmissing-format-attribute]
     212 |         ret = trace_vbprintk(ip, fmt, ap);
         |                                         ^
   include/linux/trace_printk.h:110:5: note: '__trace_bprintk' declared here
     110 | int __trace_bprintk(unsigned long ip, const char *fmt, ...);
         |     ^
   1 warning generated.


vim +212 kernel/trace/trace_printk.c

1ba28e02a18cbd kernel/trace/trace_bprintk.c Lai Jiangshan            2009-03-06  199  
48ead02030f849 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-12  200  int __trace_bprintk(unsigned long ip, const char *fmt, ...)
1427cdf0592368 kernel/trace/trace_bprintk.c Lai Jiangshan            2009-03-06  201  {
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  202  	int ret;
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  203  	va_list ap;
1427cdf0592368 kernel/trace/trace_bprintk.c Lai Jiangshan            2009-03-06  204  
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  205  	if (unlikely(!fmt))
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  206  		return 0;
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  207  
b9f9108cad3998 kernel/trace/trace_printk.c  Steven Rostedt (Red Hat  2015-09-29  208) 	if (!trace_printk_enabled)
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  209  		return 0;
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  210  
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  211  	va_start(ap, fmt);
40ce74f19c2807 kernel/trace/trace_printk.c  Steven Rostedt           2009-03-19 @212  	ret = trace_vbprintk(ip, fmt, ap);
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  213  	va_end(ap);
769b0441f438c4 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-06  214  	return ret;
1427cdf0592368 kernel/trace/trace_bprintk.c Lai Jiangshan            2009-03-06  215  }
48ead02030f849 kernel/trace/trace_printk.c  Frederic Weisbecker      2009-03-12  216  EXPORT_SYMBOL_GPL(__trace_bprintk);
1427cdf0592368 kernel/trace/trace_bprintk.c Lai Jiangshan            2009-03-06  217  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki