linux-kernel - Re: [PATCH v5 3/6] locking/rwsem: Disable preemption at all down_write*() and up

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Date:   Fri, 4 Nov 2022 04:04:01 +0800
From:   kernel test robot <lkp@...el.com>
To:     Waiman Long <longman@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will@...nel.org>,
        Boqun Feng <boqun.feng@...il.com>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        john.p.donnelly@...cle.com, Hillf Danton <hdanton@...a.com>,
        Mukesh Ojha <quic_mojha@...cinc.com>,
        Ting11 Wang 王婷 <wangting11@...omi.com>,
        Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v5 3/6] locking/rwsem: Disable preemption at all
 down_write*() and up_write() code paths

Hi Waiman,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/locking/core]
[also build test WARNING on tip/master linus/master v6.1-rc3 next-20221103]
[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/Waiman-Long/lockinig-rwsem-Fix-rwsem-bugs-enable-true-lock-handoff/20221104-023520
patch link:    https://lore.kernel.org/r/20221103182936.217120-4-longman%40redhat.com
patch subject: [PATCH v5 3/6] locking/rwsem: Disable preemption at all down_write*() and up_write() code paths
config: m68k-allyesconfig
compiler: m68k-linux-gcc (GCC) 12.1.0
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/intel-lab-lkp/linux/commit/b83e7cdb918b02166fbe3954940a7bd6f04eef14
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Waiman-Long/lockinig-rwsem-Fix-rwsem-bugs-enable-true-lock-handoff/20221104-023520
        git checkout b83e7cdb918b02166fbe3954940a7bd6f04eef14
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash kernel/locking/

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

All warnings (new ones prefixed by >>):

   kernel/locking/rwsem.c: In function '__down_write_common':
>> kernel/locking/rwsem.c:1302:13: warning: variable 'ret' set but not used [-Wunused-but-set-variable]
    1302 |         int ret = 0;
         |             ^~~


vim +/ret +1302 kernel/locking/rwsem.c

  1296	
  1297	/*
  1298	 * lock for writing
  1299	 */
  1300	static inline int __down_write_common(struct rw_semaphore *sem, int state)
  1301	{
> 1302		int ret = 0;
  1303	
  1304		preempt_disable();
  1305		if (unlikely(!rwsem_write_trylock(sem))) {
  1306			if (IS_ERR(rwsem_down_write_slowpath(sem, state)))
  1307				ret = -EINTR;
  1308		}
  1309		preempt_enable();
  1310	
  1311		return 0;
  1312	}
  1313	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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