linux-kernel - Re: [PATCH next v2 1/2] dump_stack: move cpu lock to printk.c

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Message-ID: <202106081055.UgUlUS1Z-lkp@intel.com>
Date:   Tue, 8 Jun 2021 10:43:46 +0800
From:   kernel test robot <lkp@...el.com>
To:     John Ogness <john.ogness@...utronix.de>,
        Petr Mladek <pmladek@...e.com>
Cc:     kbuild-all@...ts.01.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Marco Elver <elver@...gle.com>
Subject: Re: [PATCH next v2 1/2] dump_stack: move cpu lock to printk.c

Hi John,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20210607]

url:    https://github.com/0day-ci/linux/commits/John-Ogness/introduce-printk-cpu-lock/20210608-040454
base:    7f09e895a7f3e0af63bf9ec6c7c22893ec7e6c8e
config: mips-randconfig-r036-20210607 (attached as .config)
compiler: mips-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/136bcc2980e636b2ae156ca63fbe95c713e44c1b
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review John-Ogness/introduce-printk-cpu-lock/20210608-040454
        git checkout 136bcc2980e636b2ae156ca63fbe95c713e44c1b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   lib/dump_stack.c: In function 'dump_stack_lvl':
>> lib/dump_stack.c:107:2: warning: 'lock_flag' is used uninitialized in this function [-Wuninitialized]
     107 |  printk_cpu_unlock_irqrestore(lock_flag, irq_flags);
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/lock_flag +107 lib/dump_stack.c

    90	
    91	/**
    92	 * dump_stack - dump the current task information and its stack trace
    93	 *
    94	 * Architectures can override this implementation by implementing its own.
    95	 */
    96	asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
    97	{
    98		unsigned long irq_flags;
    99		bool lock_flag;
   100	
   101		/*
   102		 * Permit this cpu to perform nested stack dumps while serialising
   103		 * against other CPUs
   104		 */
   105		printk_cpu_lock_irqsave(&lock_flag, &irq_flags);
   106		__dump_stack(log_lvl);
 > 107		printk_cpu_unlock_irqrestore(lock_flag, irq_flags);
   108	}
   109	EXPORT_SYMBOL(dump_stack_lvl);
   110	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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