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* [paulmck-rcu:dev.2021.12.07a 56/57] kernel/rcu/tree.c:4312 rcu_cpu_starting() error: uninitialized symbol 'flags'.
@ 2021-12-10 21:57 kernel test robot
  0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2021-12-10 21:57 UTC (permalink / raw)
  To: kbuild

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CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: David Woodhouse <dwmw@amazon.co.uk>
CC: "Paul E. McKenney" <paulmck@kernel.org>

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
:::::: branch date: 28 hours ago
:::::: commit date: 28 hours ago
config: x86_64-randconfig-m001-20211210 (https://download.01.org/0day-ci/archive/20211211/202112110527.4F48SvmP-lkp(a)intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/rcu/tree.c:4312 rcu_cpu_starting() error: uninitialized symbol 'flags'.

vim +/flags +4312 kernel/rcu/tree.c

4df8374254ea92 Thomas Gleixner         2016-07-13  4266  
7ec99de36f4026 Paul E. McKenney        2016-06-30  4267  /*
7ec99de36f4026 Paul E. McKenney        2016-06-30  4268   * Mark the specified CPU as being online so that subsequent grace periods
7ec99de36f4026 Paul E. McKenney        2016-06-30  4269   * (both expedited and normal) will wait on it.  Note that this means that
7ec99de36f4026 Paul E. McKenney        2016-06-30  4270   * incoming CPUs are not allowed to use RCU read-side critical sections
7ec99de36f4026 Paul E. McKenney        2016-06-30  4271   * until this function is called.  Failing to observe this restriction
7ec99de36f4026 Paul E. McKenney        2016-06-30  4272   * will result in lockdep splats.
deb34f36439808 Paul E. McKenney        2017-03-23  4273   *
deb34f36439808 Paul E. McKenney        2017-03-23  4274   * Note that this function is special in that it is invoked directly
deb34f36439808 Paul E. McKenney        2017-03-23  4275   * from the incoming CPU rather than from the cpuhp_step mechanism.
deb34f36439808 Paul E. McKenney        2017-03-23  4276   * This is because this function must be invoked at a precise location.
7ec99de36f4026 Paul E. McKenney        2016-06-30  4277   */
7ec99de36f4026 Paul E. McKenney        2016-06-30  4278  void rcu_cpu_starting(unsigned int cpu)
7ec99de36f4026 Paul E. McKenney        2016-06-30  4279  {
342f2d0f88f3c2 David Woodhouse         2021-12-09  4280  	unsigned long flags, seq_flags;
7ec99de36f4026 Paul E. McKenney        2016-06-30  4281  	unsigned long mask;
7ec99de36f4026 Paul E. McKenney        2016-06-30  4282  	struct rcu_data *rdp;
7ec99de36f4026 Paul E. McKenney        2016-06-30  4283  	struct rcu_node *rnp;
abfce041481414 Wei Yang                2020-04-19  4284  	bool newcpu;
7ec99de36f4026 Paul E. McKenney        2016-06-30  4285  
c0f97f20e5d97a Paul E. McKenney        2020-07-24  4286  	rdp = per_cpu_ptr(&rcu_data, cpu);
c0f97f20e5d97a Paul E. McKenney        2020-07-24  4287  	if (rdp->cpu_started)
f64c6013a20293 Peter Zijlstra          2018-05-22  4288  		return;
c0f97f20e5d97a Paul E. McKenney        2020-07-24  4289  	rdp->cpu_started = true;
f64c6013a20293 Peter Zijlstra          2018-05-22  4290  
7ec99de36f4026 Paul E. McKenney        2016-06-30  4291  	rnp = rdp->mynode;
7ec99de36f4026 Paul E. McKenney        2016-06-30  4292  	mask = rdp->grpmask;
342f2d0f88f3c2 David Woodhouse         2021-12-09  4293  	local_irq_save(seq_flags);
342f2d0f88f3c2 David Woodhouse         2021-12-09  4294  	arch_spin_lock(&rcu_state.ofl_lock);
2caebefb00f03b Paul E. McKenney        2021-07-28  4295  	rcu_dynticks_eqs_online();
4d60b475f858eb Paul E. McKenney        2020-10-13  4296  	smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier().
342f2d0f88f3c2 David Woodhouse         2021-12-09  4297  	raw_spin_lock_rcu_node(rnp);
105abf82b0a626 Paul E. McKenney        2020-01-03  4298  	WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext | mask);
abfce041481414 Wei Yang                2020-04-19  4299  	newcpu = !(rnp->expmaskinitnext & mask);
7ec99de36f4026 Paul E. McKenney        2016-06-30  4300  	rnp->expmaskinitnext |= mask;
313517fc44fb2d Paul E. McKenney        2017-06-08  4301  	/* Allow lockless access for expedited grace periods. */
abfce041481414 Wei Yang                2020-04-19  4302  	smp_store_release(&rcu_state.ncpus, rcu_state.ncpus + newcpu); /* ^^^ */
2f08469563550d Paul E. McKenney        2020-02-10  4303  	ASSERT_EXCLUSIVE_WRITER(rcu_state.ncpus);
e05121ba5b81e2 Paul E. McKenney        2018-05-07  4304  	rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */
eb7a6653887b54 Paul E. McKenney        2018-07-05  4305  	rdp->rcu_onl_gp_seq = READ_ONCE(rcu_state.gp_seq);
eb7a6653887b54 Paul E. McKenney        2018-07-05  4306  	rdp->rcu_onl_gp_flags = READ_ONCE(rcu_state.gp_flags);
9f866dac94292f Joel Fernandes (Google  2020-09-29  4307) 
9f866dac94292f Joel Fernandes (Google  2020-09-29  4308) 	/* An incoming CPU should never be blocking a grace period. */
9f866dac94292f Joel Fernandes (Google  2020-09-29  4309) 	if (WARN_ON_ONCE(rnp->qsmask & mask)) { /* RCU waiting on incoming CPU? */
516e5ae0c94016 Joel Fernandes (Google  2019-09-05  4310) 		rcu_disable_urgency_upon_qs(rdp);
99990da1b3c00f Paul E. McKenney        2018-05-03  4311  		/* Report QS -after- changing ->qsmaskinitnext! */
b50912d0b5e03f Paul E. McKenney        2018-07-03 @4312  		rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags);
99990da1b3c00f Paul E. McKenney        2018-05-03  4313  	} else {
7ec99de36f4026 Paul E. McKenney        2016-06-30  4314  		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
7ec99de36f4026 Paul E. McKenney        2016-06-30  4315  	}
342f2d0f88f3c2 David Woodhouse         2021-12-09  4316  	arch_spin_unlock(&rcu_state.ofl_lock);
342f2d0f88f3c2 David Woodhouse         2021-12-09  4317  	local_irq_restore(seq_flags);
313517fc44fb2d Paul E. McKenney        2017-06-08  4318  	smp_mb(); /* Ensure RCU read-side usage follows above initialization. */
7ec99de36f4026 Paul E. McKenney        2016-06-30  4319  }
7ec99de36f4026 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(a)lists.01.org

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