Messages in this thread | | | Date | Fri, 10 Dec 2021 15:30:22 +0800 | From | kernel test robot <> | Subject | [paulmck-rcu:dev.2021.12.07a 56/57] kernel/rcu/tree.c:4312:45: warning: variable 'flags' is uninitialized when used here |
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tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2021.12.07a head: 89ddc546d3ad541bc89ec553c92036c98aef57a6 commit: 342f2d0f88f3c2d7ab2ae206be5846579319e3bf [56/57] rcu: Kill rnp->ofl_seq and use only rcu_state.ofl_lock for exclusion config: hexagon-randconfig-r041-20211210 (https://download.01.org/0day-ci/archive/20211210/202112101543.wHvqhgYk-lkp@intel.com/config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 097a1cb1d5ebb3a0ec4bcaed8ba3ff6a8e33c00a) 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://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=342f2d0f88f3c2d7ab2ae206be5846579319e3bf git remote add paulmck-rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git git fetch --no-tags paulmck-rcu dev.2021.12.07a git checkout 342f2d0f88f3c2d7ab2ae206be5846579319e3bf # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> kernel/rcu/tree.c:4312:45: warning: variable 'flags' is uninitialized when used here [-Wuninitialized] rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); ^~~~~ kernel/rcu/tree.c:4280:21: note: initialize the variable 'flags' to silence this warning unsigned long flags, seq_flags; ^ = 0 1 warning generated.
vim +/flags +4312 kernel/rcu/tree.c
4df8374254ea929 Thomas Gleixner 2016-07-13 4266 7ec99de36f40261 Paul E. McKenney 2016-06-30 4267 /* 7ec99de36f40261 Paul E. McKenney 2016-06-30 4268 * Mark the specified CPU as being online so that subsequent grace periods 7ec99de36f40261 Paul E. McKenney 2016-06-30 4269 * (both expedited and normal) will wait on it. Note that this means that 7ec99de36f40261 Paul E. McKenney 2016-06-30 4270 * incoming CPUs are not allowed to use RCU read-side critical sections 7ec99de36f40261 Paul E. McKenney 2016-06-30 4271 * until this function is called. Failing to observe this restriction 7ec99de36f40261 Paul E. McKenney 2016-06-30 4272 * will result in lockdep splats. deb34f364398083 Paul E. McKenney 2017-03-23 4273 * deb34f364398083 Paul E. McKenney 2017-03-23 4274 * Note that this function is special in that it is invoked directly deb34f364398083 Paul E. McKenney 2017-03-23 4275 * from the incoming CPU rather than from the cpuhp_step mechanism. deb34f364398083 Paul E. McKenney 2017-03-23 4276 * This is because this function must be invoked at a precise location. 7ec99de36f40261 Paul E. McKenney 2016-06-30 4277 */ 7ec99de36f40261 Paul E. McKenney 2016-06-30 4278 void rcu_cpu_starting(unsigned int cpu) 7ec99de36f40261 Paul E. McKenney 2016-06-30 4279 { 342f2d0f88f3c2d David Woodhouse 2021-12-09 4280 unsigned long flags, seq_flags; 7ec99de36f40261 Paul E. McKenney 2016-06-30 4281 unsigned long mask; 7ec99de36f40261 Paul E. McKenney 2016-06-30 4282 struct rcu_data *rdp; 7ec99de36f40261 Paul E. McKenney 2016-06-30 4283 struct rcu_node *rnp; abfce0414814149 Wei Yang 2020-04-19 4284 bool newcpu; 7ec99de36f40261 Paul E. McKenney 2016-06-30 4285 c0f97f20e5d97a1 Paul E. McKenney 2020-07-24 4286 rdp = per_cpu_ptr(&rcu_data, cpu); c0f97f20e5d97a1 Paul E. McKenney 2020-07-24 4287 if (rdp->cpu_started) f64c6013a202931 Peter Zijlstra 2018-05-22 4288 return; c0f97f20e5d97a1 Paul E. McKenney 2020-07-24 4289 rdp->cpu_started = true; f64c6013a202931 Peter Zijlstra 2018-05-22 4290 7ec99de36f40261 Paul E. McKenney 2016-06-30 4291 rnp = rdp->mynode; 7ec99de36f40261 Paul E. McKenney 2016-06-30 4292 mask = rdp->grpmask; 342f2d0f88f3c2d David Woodhouse 2021-12-09 4293 local_irq_save(seq_flags); 342f2d0f88f3c2d David Woodhouse 2021-12-09 4294 arch_spin_lock(&rcu_state.ofl_lock); 2caebefb00f03b5 Paul E. McKenney 2021-07-28 4295 rcu_dynticks_eqs_online(); 4d60b475f858ebd Paul E. McKenney 2020-10-13 4296 smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier(). 342f2d0f88f3c2d David Woodhouse 2021-12-09 4297 raw_spin_lock_rcu_node(rnp); 105abf82b0a6266 Paul E. McKenney 2020-01-03 4298 WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext | mask); abfce0414814149 Wei Yang 2020-04-19 4299 newcpu = !(rnp->expmaskinitnext & mask); 7ec99de36f40261 Paul E. McKenney 2016-06-30 4300 rnp->expmaskinitnext |= mask; 313517fc44fb2d8 Paul E. McKenney 2017-06-08 4301 /* Allow lockless access for expedited grace periods. */ abfce0414814149 Wei Yang 2020-04-19 4302 smp_store_release(&rcu_state.ncpus, rcu_state.ncpus + newcpu); /* ^^^ */ 2f08469563550d1 Paul E. McKenney 2020-02-10 4303 ASSERT_EXCLUSIVE_WRITER(rcu_state.ncpus); e05121ba5b81e2f Paul E. McKenney 2018-05-07 4304 rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */ eb7a6653887b540 Paul E. McKenney 2018-07-05 4305 rdp->rcu_onl_gp_seq = READ_ONCE(rcu_state.gp_seq); eb7a6653887b540 Paul E. McKenney 2018-07-05 4306 rdp->rcu_onl_gp_flags = READ_ONCE(rcu_state.gp_flags); 9f866dac94292f9 Joel Fernandes (Google 2020-09-29 4307) 9f866dac94292f9 Joel Fernandes (Google 2020-09-29 4308) /* An incoming CPU should never be blocking a grace period. */ 9f866dac94292f9 Joel Fernandes (Google 2020-09-29 4309) if (WARN_ON_ONCE(rnp->qsmask & mask)) { /* RCU waiting on incoming CPU? */ 516e5ae0c940162 Joel Fernandes (Google 2019-09-05 4310) rcu_disable_urgency_upon_qs(rdp); 99990da1b3c00f6 Paul E. McKenney 2018-05-03 4311 /* Report QS -after- changing ->qsmaskinitnext! */ b50912d0b5e03f1 Paul E. McKenney 2018-07-03 @4312 rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); 99990da1b3c00f6 Paul E. McKenney 2018-05-03 4313 } else { 7ec99de36f40261 Paul E. McKenney 2016-06-30 4314 raw_spin_unlock_irqrestore_rcu_node(rnp, flags); 7ec99de36f40261 Paul E. McKenney 2016-06-30 4315 } 342f2d0f88f3c2d David Woodhouse 2021-12-09 4316 arch_spin_unlock(&rcu_state.ofl_lock); 342f2d0f88f3c2d David Woodhouse 2021-12-09 4317 local_irq_restore(seq_flags); 313517fc44fb2d8 Paul E. McKenney 2017-06-08 4318 smp_mb(); /* Ensure RCU read-side usage follows above initialization. */ 7ec99de36f40261 Paul E. McKenney 2016-06-30 4319 } 7ec99de36f40261 Paul E. McKenney 2016-06-30 4320
:::::: The code at line 4312 was first introduced by commit :::::: b50912d0b5e03f11004fec1e2b50244de9e2fa41 rcu: Remove rsp parameter from rcu_report_qs_rnp()
:::::: TO: Paul E. McKenney <paulmck@linux.vnet.ibm.com> :::::: CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
--- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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