sched: allow cpuacct stats to be reset

Currently the schedstats implementation does not allow the statistics
to be reset. This patch aims to allow that.

  echo 0 > cpuacct.usage

resets the usage. Any other value is not allowed and returns -EINVAL.

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 24 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index e2f85c7a7476..e4bf4477aee5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8381,10 +8381,34 @@ static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
         return totalcpuusage;
 }
 
+static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
+                                                                u64 reset)
+{
+        struct cpuacct *ca = cgroup_ca(cgrp);
+        int err = 0;
+        int i;
+
+        if (reset) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        for_each_possible_cpu(i) {
+                u64 *cpuusage = percpu_ptr(ca->cpuusage, i);
+
+                spin_lock_irq(&cpu_rq(i)->lock);
+                *cpuusage = 0;
+                spin_unlock_irq(&cpu_rq(i)->lock);
+        }
+out:
+        return err;
+}
+
 static struct cftype files[] = {
         {
                 .name = "usage",
                 .read_uint = cpuusage_read,
+                .write_uint = cpuusage_write,
         },
 };