cgroup/rstat: Fix forceidle time in cpu.stat

The commit b824766504e4 ("cgroup/rstat: add force idle show helper")
retrieves forceidle_time outside cgroup_rstat_lock for non-root cgroups
which can be potentially inconsistent with other stats.

Rather than reverting that commit, fix it in a way that retains the
effort of cleaning up the ifdef-messes.

Fixes: b824766504e4 ("cgroup/rstat: add force idle show helper")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 5877974ece92c6ae3c6313039a6f866777d575ef..c2784c317cddf0c747d01f977f615cadf946ad5b 100644 (file)
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -613,36 +613,33 @@ static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat
 void cgroup_base_stat_cputime_show(struct seq_file *seq)
 {
        struct cgroup *cgrp = seq_css(seq)->cgroup;
-       u64 usage, utime, stime, ntime;
+       struct cgroup_base_stat bstat;
 
        if (cgroup_parent(cgrp)) {
                cgroup_rstat_flush_hold(cgrp);
-               usage = cgrp->bstat.cputime.sum_exec_runtime;
+               bstat = cgrp->bstat;
                cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
-                              &utime, &stime);
-               ntime = cgrp->bstat.ntime;
+                              &bstat.cputime.utime, &bstat.cputime.stime);
                cgroup_rstat_flush_release(cgrp);
        } else {
-               /* cgrp->bstat of root is not actually used, reuse it */
-               root_cgroup_cputime(&cgrp->bstat);
-               usage = cgrp->bstat.cputime.sum_exec_runtime;
-               utime = cgrp->bstat.cputime.utime;
-               stime = cgrp->bstat.cputime.stime;
-               ntime = cgrp->bstat.ntime;
+               root_cgroup_cputime(&bstat);
        }
 
-       do_div(usage, NSEC_PER_USEC);
-       do_div(utime, NSEC_PER_USEC);
-       do_div(stime, NSEC_PER_USEC);
-       do_div(ntime, NSEC_PER_USEC);
+       do_div(bstat.cputime.sum_exec_runtime, NSEC_PER_USEC);
+       do_div(bstat.cputime.utime, NSEC_PER_USEC);
+       do_div(bstat.cputime.stime, NSEC_PER_USEC);
+       do_div(bstat.ntime, NSEC_PER_USEC);
 
        seq_printf(seq, "usage_usec %llu\n"
                        "user_usec %llu\n"
                        "system_usec %llu\n"
                        "nice_usec %llu\n",
-                       usage, utime, stime, ntime);
+                       bstat.cputime.sum_exec_runtime,
+                       bstat.cputime.utime,
+                       bstat.cputime.stime,
+                       bstat.ntime);
 
-       cgroup_force_idle_show(seq, &cgrp->bstat);
+       cgroup_force_idle_show(seq, &bstat);
 }
 
 /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */