[PATCH 2/4] bpf: add bpf_cgroup_{flush_stats,stall} function

[Vernon Yang]

From: Vernon Yang <yanglincheng@xxxxxxxxxx>

Add bpf_cgroup_{flush_stats,stall} function to prepare for the
subsequent mthp_ext ebpf program.

no function changes.

Signed-off-by: Vernon Yang <yanglincheng@xxxxxxxxxx>
---
 kernel/bpf/helpers.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 2bb60200c266..87f3072adce3 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -29,6 +29,7 @@
 #include <linux/task_work.h>
 #include <linux/irq_work.h>
 #include <linux/buildid.h>
+#include <linux/psi.h>
 
 #include "../../lib/kstrtox.h"
 
@@ -2819,6 +2820,32 @@ __bpf_kfunc struct cgroup *bpf_cgroup_from_id(u64 cgid)
 	return cgrp;
 }
 
+/**
+ * bpf_cgroup_stall - acquire the total stall time of cgroup
+ * @cgrp: cgroup struct
+ * @states: psi states
+ *
+ * Return the total stall time.
+ */
+__bpf_kfunc unsigned long bpf_cgroup_stall(struct cgroup *cgrp,
+					   enum psi_states states)
+{
+	struct psi_group *group = cgroup_psi(cgrp);
+
+	return div_u64(group->total[PSI_AVGS][states], NSEC_PER_MSEC);
+}
+
+/**
+ * bpf_cgroup_flush_stats - Flush cgroup's statistics
+ * @cgrp: cgroup struct
+ */
+__bpf_kfunc void bpf_cgroup_flush_stats(struct cgroup *cgrp)
+{
+	struct psi_group *group = cgroup_psi(cgrp);
+
+	psi_group_flush_stats(group);
+}
+
 /**
  * bpf_task_under_cgroup - wrap task_under_cgroup_hierarchy() as a kfunc, test
  * task's membership of cgroup ancestry.
@@ -4732,6 +4759,8 @@ BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_cgroup_release, KF_RELEASE)
 BTF_ID_FLAGS(func, bpf_cgroup_ancestor, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_cgroup_from_id, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_cgroup_stall)
+BTF_ID_FLAGS(func, bpf_cgroup_flush_stats, KF_SLEEPABLE)
 BTF_ID_FLAGS(func, bpf_task_under_cgroup, KF_RCU)
 BTF_ID_FLAGS(func, bpf_task_get_cgroup1, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
 #endif
-- 
2.53.0