From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-6.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gnuweeb.org (Postfix) with ESMTPS id 9655A8061E for ; Thu, 25 Aug 2022 04:30:22 +0000 (UTC) Authentication-Results: gnuweeb.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=UEufDrSP; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661401822; x=1692937822; h=date:from:to:cc:subject:message-id:mime-version; bh=Kxq4UxK/+sKN/MKITgtaEMVYFGyFYzE9EZkADoyRsCo=; b=UEufDrSPcbiQbVERiaT32uJujR2GTf5APmJNkdmdB3YX8bIf/+sV5zu6 kWIl708C79YOhPEkzh5vq2t296/dj+qaJzaYxVy4PR0rml2F3PyDIzPmd VYZREQmzITZYHcXk+El8YZiqApD0dYxqJxcyOAXX/LeUn15MTNzN9KI+I ccqLMtxoGrQjBKawL9ZFj46oysc+qkpI+noZof0RY3ozy3zOWvWTmIMjA jT3KQ0JOFxj0Wo/dLx+jiJrjfzP5hCSGR8jjvIgyd0SZBvpfhCIC3biW1 jSg+S9BMssoCj3N5WHpL0uudgjSlO9T5ooMln8fG7J5Bs8Bp+rIInI4mq A==; X-IronPort-AV: E=McAfee;i="6500,9779,10449"; a="294143353" X-IronPort-AV: E=Sophos;i="5.93,262,1654585200"; d="scan'208";a="294143353" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2022 21:30:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,262,1654585200"; d="scan'208";a="610023194" Received: from lkp-server02.sh.intel.com (HELO 34e741d32628) ([10.239.97.151]) by orsmga002.jf.intel.com with ESMTP; 24 Aug 2022 21:30:18 -0700 Received: from kbuild by 34e741d32628 with local (Exim 4.96) (envelope-from ) id 1oR4VV-0001i9-27; Thu, 25 Aug 2022 04:30:17 +0000 Date: Thu, 25 Aug 2022 12:30:10 +0800 From: kernel test robot To: Uros Bizjak Cc: llvm@lists.linux.dev, kbuild-all@lists.01.org, Ammar Faizi , GNU/Weeb Mailing List , linux-kernel@vger.kernel.org, Andrew Morton , Linux Memory Management List Subject: [ammarfaizi2-block:akpm/mm/mm-nonmm-unstable 50/50] kernel/smpboot.c:435:6: warning: variable 'oldstate' is used uninitialized whenever 'if' condition is true Message-ID: <202208251224.teVMa7Yy-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline List-Id: Hi Uros, FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant. tree: https://github.com/ammarfaizi2/linux-block akpm/mm/mm-nonmm-unstable head: 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc commit: 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc [50/50] smpboot: use atomic_try_cmpxchg in cpu_wait_death and cpu_report_death config: x86_64-randconfig-a003 (https://download.01.org/0day-ci/archive/20220825/202208251224.teVMa7Yy-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/ammarfaizi2/linux-block/commit/2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block git fetch --no-tags ammarfaizi2-block akpm/mm/mm-nonmm-unstable git checkout 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc # 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=x86_64 SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> kernel/smpboot.c:435:6: warning: variable 'oldstate' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/smpboot.c:449:6: note: uninitialized use occurs here if (oldstate == CPU_DEAD) { ^~~~~~~~ kernel/smpboot.c:435:2: note: remove the 'if' if its condition is always false if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/smpboot.c:428:14: note: initialize the variable 'oldstate' to silence this warning int oldstate; ^ = 0 1 warning generated. vim +435 kernel/smpboot.c 8038dad7e88858 Paul E. McKenney 2015-02-25 421 8038dad7e88858 Paul E. McKenney 2015-02-25 422 /* 8038dad7e88858 Paul E. McKenney 2015-02-25 423 * Wait for the specified CPU to exit the idle loop and die. 8038dad7e88858 Paul E. McKenney 2015-02-25 424 */ 8038dad7e88858 Paul E. McKenney 2015-02-25 425 bool cpu_wait_death(unsigned int cpu, int seconds) 8038dad7e88858 Paul E. McKenney 2015-02-25 426 { 8038dad7e88858 Paul E. McKenney 2015-02-25 427 int jf_left = seconds * HZ; 8038dad7e88858 Paul E. McKenney 2015-02-25 428 int oldstate; 8038dad7e88858 Paul E. McKenney 2015-02-25 429 bool ret = true; 8038dad7e88858 Paul E. McKenney 2015-02-25 430 int sleep_jf = 1; 8038dad7e88858 Paul E. McKenney 2015-02-25 431 8038dad7e88858 Paul E. McKenney 2015-02-25 432 might_sleep(); 8038dad7e88858 Paul E. McKenney 2015-02-25 433 8038dad7e88858 Paul E. McKenney 2015-02-25 434 /* The outgoing CPU will normally get done quite quickly. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 @435 if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) 8038dad7e88858 Paul E. McKenney 2015-02-25 436 goto update_state; 8038dad7e88858 Paul E. McKenney 2015-02-25 437 udelay(5); 8038dad7e88858 Paul E. McKenney 2015-02-25 438 8038dad7e88858 Paul E. McKenney 2015-02-25 439 /* But if the outgoing CPU dawdles, wait increasingly long times. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 440 while (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) != CPU_DEAD) { 8038dad7e88858 Paul E. McKenney 2015-02-25 441 schedule_timeout_uninterruptible(sleep_jf); 8038dad7e88858 Paul E. McKenney 2015-02-25 442 jf_left -= sleep_jf; 8038dad7e88858 Paul E. McKenney 2015-02-25 443 if (jf_left <= 0) 8038dad7e88858 Paul E. McKenney 2015-02-25 444 break; 8038dad7e88858 Paul E. McKenney 2015-02-25 445 sleep_jf = DIV_ROUND_UP(sleep_jf * 11, 10); 8038dad7e88858 Paul E. McKenney 2015-02-25 446 } 8038dad7e88858 Paul E. McKenney 2015-02-25 447 oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu)); 2d1e07c7534c14 Uros Bizjak 2022-08-23 448 update_state: 8038dad7e88858 Paul E. McKenney 2015-02-25 449 if (oldstate == CPU_DEAD) { 8038dad7e88858 Paul E. McKenney 2015-02-25 450 /* Outgoing CPU died normally, update state. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 451 smp_mb(); /* atomic_read() before update. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 452 atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_POST_DEAD); 8038dad7e88858 Paul E. McKenney 2015-02-25 453 } else { 8038dad7e88858 Paul E. McKenney 2015-02-25 454 /* Outgoing CPU still hasn't died, set state accordingly. */ 2d1e07c7534c14 Uros Bizjak 2022-08-23 455 if (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu), 2d1e07c7534c14 Uros Bizjak 2022-08-23 456 &oldstate, CPU_BROKEN)) 8038dad7e88858 Paul E. McKenney 2015-02-25 457 goto update_state; 8038dad7e88858 Paul E. McKenney 2015-02-25 458 ret = false; 8038dad7e88858 Paul E. McKenney 2015-02-25 459 } 8038dad7e88858 Paul E. McKenney 2015-02-25 460 return ret; 8038dad7e88858 Paul E. McKenney 2015-02-25 461 } 8038dad7e88858 Paul E. McKenney 2015-02-25 462 :::::: The code at line 435 was first introduced by commit :::::: 8038dad7e888581266c76df15d70ca457a3c5910 smpboot: Add common code for notification from dying CPU :::::: TO: Paul E. McKenney :::::: CC: Paul E. McKenney -- 0-DAY CI Kernel Test Service https://01.org/lkp