[vincent.guittot:test/scheduler 69/74] kernel/sched/fair.c:6185 select_idle_cpu() error: uninitialized symbol 'time'.

[kernel test robot <lkp@intel.com>]

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CC: kbuild-all(a)lists.01.org
TO: Mel Gorman <mgorman@suse.de>
CC: Vincent Guittot <vincent.guittot@linaro.org>

tree:   https://git.linaro.org/people/vincent.guittot/kernel.git test/scheduler
head:   cfb162fefb7647f2c8e78681ece781233aa88eb3
commit: 490dadb841cb68eca010bad64758f679483d1c10 [69/74] sched/fair: Move avg_scan_cost calculations under SIS_PROP
:::::: branch date: 22 hours ago
:::::: commit date: 3 days ago
config: x86_64-randconfig-m001-20201209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 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/sched/fair.c:6185 select_idle_cpu() error: uninitialized symbol 'time'.

vim +/time +6185 kernel/sched/fair.c

10e2f1acd0106c Peter Zijlstra     2016-05-09  6138  
10e2f1acd0106c Peter Zijlstra     2016-05-09  6139  /*
10e2f1acd0106c Peter Zijlstra     2016-05-09  6140   * Scan the LLC domain for idle CPUs; this is dynamically regulated by
10e2f1acd0106c Peter Zijlstra     2016-05-09  6141   * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
10e2f1acd0106c Peter Zijlstra     2016-05-09  6142   * average idle time for this rq (as found in rq->avg_idle).
10e2f1acd0106c Peter Zijlstra     2016-05-09  6143   */
10e2f1acd0106c Peter Zijlstra     2016-05-09  6144  static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target)
10e2f1acd0106c Peter Zijlstra     2016-05-09  6145  {
60588bfa223ff6 Cheng Jian         2019-12-13  6146  	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
9cfb38a7ba5a9c Wanpeng Li         2016-10-09  6147  	struct sched_domain *this_sd;
d76343c6b2b79f Valentin Schneider 2020-03-30  6148  	u64 time;
8dc2d993cf1aea Peter Zijlstra     2019-02-27  6149  	int this = smp_processor_id();
17346452b25b98 Viresh Kumar       2019-11-14  6150  	int cpu, nr = INT_MAX;
10e2f1acd0106c Peter Zijlstra     2016-05-09  6151  
9cfb38a7ba5a9c Wanpeng Li         2016-10-09  6152  	this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
9cfb38a7ba5a9c Wanpeng Li         2016-10-09  6153  	if (!this_sd)
9cfb38a7ba5a9c Wanpeng Li         2016-10-09  6154  		return -1;
9cfb38a7ba5a9c Wanpeng Li         2016-10-09  6155  
490dadb841cb68 Mel Gorman         2020-12-08  6156  	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
490dadb841cb68 Mel Gorman         2020-12-08  6157  
321178b2549dd6 Mel Gorman         2020-12-08  6158  	if (sched_feat(SIS_PROP)) {
321178b2549dd6 Mel Gorman         2020-12-08  6159  		u64 avg_cost, avg_idle, span_avg;
321178b2549dd6 Mel Gorman         2020-12-08  6160  
10e2f1acd0106c Peter Zijlstra     2016-05-09  6161  		/*
321178b2549dd6 Mel Gorman         2020-12-08  6162  		 * Due to large variance we need a large fuzz factor;
321178b2549dd6 Mel Gorman         2020-12-08  6163  		 * hackbench in particularly is sensitive here.
10e2f1acd0106c Peter Zijlstra     2016-05-09  6164  		 */
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6165  		avg_idle = this_rq()->avg_idle / 512;
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6166  		avg_cost = this_sd->avg_scan_cost + 1;
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6167  
321178b2549dd6 Mel Gorman         2020-12-08  6168  		span_avg = sd->span_weight * avg_idle;
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6169  		if (span_avg > 4*avg_cost)
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6170  			nr = div_u64(span_avg, avg_cost);
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6171  		else
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6172  			nr = 4;
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6173  
8dc2d993cf1aea Peter Zijlstra     2019-02-27  6174  		time = cpu_clock(this);
490dadb841cb68 Mel Gorman         2020-12-08  6175  	}
60588bfa223ff6 Cheng Jian         2019-12-13  6176  
60588bfa223ff6 Cheng Jian         2019-12-13  6177  	for_each_cpu_wrap(cpu, cpus, target) {
1ad3aaf3fcd244 Peter Zijlstra     2017-05-17  6178  		if (!--nr)
17346452b25b98 Viresh Kumar       2019-11-14  6179  			return -1;
17346452b25b98 Viresh Kumar       2019-11-14  6180  		if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
10e2f1acd0106c Peter Zijlstra     2016-05-09  6181  			break;
10e2f1acd0106c Peter Zijlstra     2016-05-09  6182  	}
10e2f1acd0106c Peter Zijlstra     2016-05-09  6183  
490dadb841cb68 Mel Gorman         2020-12-08  6184  	if (sched_feat(SIS_PROP)) {
8dc2d993cf1aea Peter Zijlstra     2019-02-27 @6185  		time = cpu_clock(this) - time;
d76343c6b2b79f Valentin Schneider 2020-03-30  6186  		update_avg(&this_sd->avg_scan_cost, time);
490dadb841cb68 Mel Gorman         2020-12-08  6187  	}
10e2f1acd0106c Peter Zijlstra     2016-05-09  6188  
10e2f1acd0106c Peter Zijlstra     2016-05-09  6189  	return cpu;
10e2f1acd0106c Peter Zijlstra     2016-05-09  6190  }
10e2f1acd0106c Peter Zijlstra     2016-05-09  6191  

:::::: The code at line 6185 was first introduced by commit
:::::: 8dc2d993cf1aea578d947e34ea2d5c6ffd1644e4 x86/percpu, sched/fair: Avoid local_clock()

:::::: TO: Peter Zijlstra <peterz@infradead.org>
:::::: CC: Ingo Molnar <mingo@kernel.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
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