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rcuscale: Console output claims too few grace periods

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[ Upstream commit 811192c5f24bfd7246ce9ce06f668d8c408bf39b ]

The rcuscale console output claims N grace periods, numbered from zero
to N, which means that there were really N+1 grace periods.  The root
cause of this bug is that rcu_scale_writer() stores the number of the
last grace period (numbered from zero) into writer_n_durations[me]
instead of the number of grace periods.  This commit therefore assigns
the actual number of grace periods to writer_n_durations[me], and also
makes the corresponding adjustment to the loop outputting per-grace-period
measurements.

Sample of old console output:
    rcu-scale: writer 0 gps: 133
    ......
    rcu-scale:    0 writer-duration:     0 44003961
    rcu-scale:    0 writer-duration:     1 32003582
    ......
    rcu-scale:    0 writer-duration:   132 28004391
    rcu-scale:    0 writer-duration:   133 27996410

Sample of new console output:
    rcu-scale: writer 0 gps: 134
    ......
    rcu-scale:    0 writer-duration:     0 44003961
    rcu-scale:    0 writer-duration:     1 32003582
    ......
    rcu-scale:    0 writer-duration:   132 28004391
    rcu-scale:    0 writer-duration:   133 27996410

Signed-off-by: Jiangong.Han <jiangong.han@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Stable-dep-of: 23fc8df26dea ("rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jiangong.Han 2021-06-22 18:37:08 +08:00 committed by Greg Kroah-Hartman
parent 456f783b83
commit 8cd9917c13
1 changed files with 2 additions and 2 deletions
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4
kernel/rcu/rcuscale.c
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@ -457,7 +457,7 @@ rcu_scale_writer(void *arg)
if (gp_async) {
cur_ops->gp_barrier();
}
writer_n_durations[me] = i_max;
writer_n_durations[me] = i_max + 1;
torture_kthread_stopping("rcu_scale_writer");
return 0;
}
@ -531,7 +531,7 @@ rcu_scale_cleanup(void)
wdpp = writer_durations[i];
if (!wdpp)
continue;
for (j = 0; j <= writer_n_durations[i]; j++) {
for (j = 0; j < writer_n_durations[i]; j++) {
wdp = &wdpp[j];
pr_alert("%s%s %4d writer-duration: %5d %llu\n",
scale_type, SCALE_FLAG,