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TO: Zqiang <[email protected]>
TO: [email protected]
TO: [email protected]
CC: [email protected]
CC: [email protected]

Hi Zqiang,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on paulmck-rcu/dev]
[also build test WARNING on v5.18-rc3 next-20220422]
[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]

url:    
https://github.com/intel-lab-lkp/linux/commits/Zqiang/rcu-Dump-all-rcuc-kthreads-status-for-CPUs-that-not-report-quiescent-state/20220424-121850
base:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git 
dev
:::::: branch date: 4 hours ago
:::::: commit date: 4 hours ago
config: i386-randconfig-m021 
(https://download.01.org/0day-ci/archive/20220424/[email protected]/config)
compiler: gcc-11 (Debian 11.2.0-20) 11.2.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>

smatch warnings:
kernel/rcu/tree_stall.h:467 print_cpu_stall_info() error: uninitialized symbol 
'j'.

vim +/j +467 kernel/rcu/tree_stall.h

c9515875850fef Zqiang           2022-01-25  428  
59b73a27681c58 Paul E. McKenney 2019-01-11  429  /*
59b73a27681c58 Paul E. McKenney 2019-01-11  430   * Print out diagnostic 
information for the specified stalled CPU.
59b73a27681c58 Paul E. McKenney 2019-01-11  431   *
59b73a27681c58 Paul E. McKenney 2019-01-11  432   * If the specified CPU is 
aware of the current RCU grace period, then
59b73a27681c58 Paul E. McKenney 2019-01-11  433   * print the number of 
scheduling clock interrupts the CPU has taken
59b73a27681c58 Paul E. McKenney 2019-01-11  434   * during the time that it has 
been aware.  Otherwise, print the number
59b73a27681c58 Paul E. McKenney 2019-01-11  435   * of RCU grace periods that 
this CPU is ignorant of, for example, "1"
59b73a27681c58 Paul E. McKenney 2019-01-11  436   * if the CPU was aware of the 
previous grace period.
59b73a27681c58 Paul E. McKenney 2019-01-11  437   *
e2c73a6860bdf5 Paul E. McKenney 2021-09-27  438   * Also print out idle info.
59b73a27681c58 Paul E. McKenney 2019-01-11  439   */
59b73a27681c58 Paul E. McKenney 2019-01-11  440  static void 
print_cpu_stall_info(int cpu)
59b73a27681c58 Paul E. McKenney 2019-01-11  441  {
59b73a27681c58 Paul E. McKenney 2019-01-11  442         unsigned long delta;
88375825171c7d Paul E. McKenney 2020-03-31  443         bool falsepositive;
59b73a27681c58 Paul E. McKenney 2019-01-11  444         struct rcu_data *rdp = 
per_cpu_ptr(&rcu_data, cpu);
59b73a27681c58 Paul E. McKenney 2019-01-11  445         char *ticks_title;
59b73a27681c58 Paul E. McKenney 2019-01-11  446         unsigned long 
ticks_value;
17d9de741a1aaf Zqiang           2022-04-24  447         bool rcuc_starved;
17d9de741a1aaf Zqiang           2022-04-24  448         unsigned long j;
59b73a27681c58 Paul E. McKenney 2019-01-11  449  
59b73a27681c58 Paul E. McKenney 2019-01-11  450         /*
59b73a27681c58 Paul E. McKenney 2019-01-11  451          * We could be printing 
a lot while holding a spinlock.  Avoid
59b73a27681c58 Paul E. McKenney 2019-01-11  452          * triggering hard 
lockup.
59b73a27681c58 Paul E. McKenney 2019-01-11  453          */
59b73a27681c58 Paul E. McKenney 2019-01-11  454         touch_nmi_watchdog();
59b73a27681c58 Paul E. McKenney 2019-01-11  455  
59b73a27681c58 Paul E. McKenney 2019-01-11  456         ticks_value = 
rcu_seq_ctr(rcu_state.gp_seq - rdp->gp_seq);
59b73a27681c58 Paul E. McKenney 2019-01-11  457         if (ticks_value) {
59b73a27681c58 Paul E. McKenney 2019-01-11  458                 ticks_title = 
"GPs behind";
59b73a27681c58 Paul E. McKenney 2019-01-11  459         } else {
59b73a27681c58 Paul E. McKenney 2019-01-11  460                 ticks_title = 
"ticks this GP";
59b73a27681c58 Paul E. McKenney 2019-01-11  461                 ticks_value = 
rdp->ticks_this_gp;
59b73a27681c58 Paul E. McKenney 2019-01-11  462         }
59b73a27681c58 Paul E. McKenney 2019-01-11  463         delta = 
rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
88375825171c7d Paul E. McKenney 2020-03-31  464         falsepositive = 
rcu_is_gp_kthread_starving(NULL) &&
88375825171c7d Paul E. McKenney 2020-03-31  465                         
rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
17d9de741a1aaf Zqiang           2022-04-24  466         rcuc_starved = 
rcu_is_rcuc_kthread_starving(rdp, &j);
17d9de741a1aaf Zqiang           2022-04-24 @467         pr_err("\t%d-%c%c%c%c: 
(%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld rcuc=%ld jiffies(%s) %s\n",
59b73a27681c58 Paul E. McKenney 2019-01-11  468                cpu,
59b73a27681c58 Paul E. McKenney 2019-01-11  469                
"O."[!!cpu_online(cpu)],
59b73a27681c58 Paul E. McKenney 2019-01-11  470                
"o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
59b73a27681c58 Paul E. McKenney 2019-01-11  471                
"N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
59b73a27681c58 Paul E. McKenney 2019-01-11  472                
!IS_ENABLED(CONFIG_IRQ_WORK) ? '?' :
59b73a27681c58 Paul E. McKenney 2019-01-11  473                         
rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
59b73a27681c58 Paul E. McKenney 2019-01-11  474                                 
"!."[!delta],
59b73a27681c58 Paul E. McKenney 2019-01-11  475                ticks_value, 
ticks_title,
59b73a27681c58 Paul E. McKenney 2019-01-11  476                
rcu_dynticks_snap(rdp) & 0xfff,
59b73a27681c58 Paul E. McKenney 2019-01-11  477                
rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
59b73a27681c58 Paul E. McKenney 2019-01-11  478                
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
88375825171c7d Paul E. McKenney 2020-03-31  479                
data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
17d9de741a1aaf Zqiang           2022-04-24  480                j, rcuc_starved 
? "starved" : "",
88375825171c7d Paul E. McKenney 2020-03-31  481                falsepositive ? 
" (false positive?)" : "");
59b73a27681c58 Paul E. McKenney 2019-01-11  482  }
59b73a27681c58 Paul E. McKenney 2019-01-11  483  

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