linux-kernel - Re: [PATCH 4/4] audit: check if queue is full after prepare_to_wait

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Date:   Tue, 9 May 2023 01:13:11 +0800
From:   kernel test robot <lkp@...el.com>
To:     Eiichi Tsukata <eiichi.tsukata@...anix.com>, paul@...l-moore.com,
        eparis@...hat.com, linux-kernel@...r.kernel.org,
        audit@...r.kernel.org
Cc:     llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
        Eiichi Tsukata <eiichi.tsukata@...anix.com>
Subject: Re: [PATCH 4/4] audit: check if queue is full after
 prepare_to_wait_exclusive()

Hi Eiichi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on pcmoore-audit/next]
[also build test WARNING on linus/master v6.4-rc1 next-20230508]
[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/Eiichi-Tsukata/audit-refactor-queue-full-checks/20230508-160019
base:   https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git next
patch link:    https://lore.kernel.org/r/20230508075812.76077-5-eiichi.tsukata%40nutanix.com
patch subject: [PATCH 4/4] audit: check if queue is full after prepare_to_wait_exclusive()
config: i386-randconfig-a001-20230508 (https://download.01.org/0day-ci/archive/20230509/202305090112.uJSc0NBw-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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/intel-lab-lkp/linux/commit/cbc69d0c34bdbc06ebca3e3020cfc24034fcf173
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Eiichi-Tsukata/audit-refactor-queue-full-checks/20230508-160019
        git checkout cbc69d0c34bdbc06ebca3e3020cfc24034fcf173
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202305090112.uJSc0NBw-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/audit.c:651:6: warning: variable 'rtime' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (audit_queue_full(&audit_queue)) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/audit.c:657:9: note: uninitialized use occurs here
           return rtime;
                  ^~~~~
   kernel/audit.c:651:2: note: remove the 'if' if its condition is always true
           if (audit_queue_full(&audit_queue)) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/audit.c:642:12: note: initialize the variable 'rtime' to silence this warning
           long rtime;
                     ^
                      = 0
   1 warning generated.


vim +651 kernel/audit.c

   630	
   631	/**
   632	 * wait_for_kauditd - Wait for kauditd to drain the queue
   633	 * @stime: time to sleep
   634	 *
   635	 * Description:
   636	 * Waits for kauditd to drain the queue then adds duration of sleep time to
   637	 * audit_backlog_wait_time_actual as cumulative sum.
   638	 * Returns remaining time to sleep.
   639	 */
   640	static long wait_for_kauditd(long stime)
   641	{
   642		long rtime;
   643		DEFINE_WAIT(wait);
   644	
   645		prepare_to_wait_exclusive(&audit_backlog_wait, &wait,
   646					  TASK_UNINTERRUPTIBLE);
   647	
   648		/* need to check if the queue is full again because kauditd might have
   649		 * flushed the queue and went to sleep after prepare_to_wait_exclusive()
   650		 */
 > 651		if (audit_queue_full(&audit_queue)) {
   652			rtime = schedule_timeout(stime);
   653			atomic_add(stime - rtime, &audit_backlog_wait_time_actual);
   654		}
   655		finish_wait(&audit_backlog_wait, &wait);
   656	
   657		return rtime;
   658	}
   659	

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