On 5/19/22 6:21 PM, Yosry Ahmed wrote:
Add cgroup_rstat_updated() and cgroup_rstat_flush() kfuncs to bpf
tracing programs. bpf programs that make use of rstat can use these
functions to inform rstat when they update stats for a cgroup, and when
they need to flush the stats.
Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
---
kernel/cgroup/rstat.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index e7a88d2600bd..a16a851bc0a1 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -3,6 +3,11 @@
#include <linux/sched/cputime.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+
+
static DEFINE_SPINLOCK(cgroup_rstat_lock);
static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
@@ -141,7 +146,12 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
return pos;
}
-/* A hook for bpf stat collectors to attach to and flush their stats */
+/*
+ * A hook for bpf stat collectors to attach to and flush their stats.
+ * Together with providing bpf kfuncs for cgroup_rstat_updated() and
+ * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
+ * collect cgroup stats can integrate with rstat for efficient flushing.
+ */
__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
struct cgroup *parent, int cpu)
{
@@ -476,3 +486,26 @@ void cgroup_base_stat_cputime_show(struct seq_file *seq)
"system_usec %llu\n",
usage, utime, stime);
}
+
+/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
+BTF_SET_START(bpf_rstat_check_kfunc_ids)
+BTF_ID(func, cgroup_rstat_updated)
+BTF_ID(func, cgroup_rstat_flush)
+BTF_SET_END(bpf_rstat_check_kfunc_ids)
+
+BTF_SET_START(bpf_rstat_sleepable_kfunc_ids)
+BTF_ID(func, cgroup_rstat_flush)
+BTF_SET_END(bpf_rstat_sleepable_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
+ .owner = THIS_MODULE,
+ .check_set = &bpf_rstat_check_kfunc_ids,
+ .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
There is a compilation error here:
kernel/cgroup/rstat.c:503:3: error: ‘const struct btf_kfunc_id_set’ has
no member named ‘sleepable_set’; did you mean ‘release_set’?
503 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^~~~~~~~~~~~~
| release_set
kernel/cgroup/rstat.c:503:19: warning: excess elements in struct
initializer
503 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^
kernel/cgroup/rstat.c:503:19: note: (near initialization for
‘bpf_rstat_kfunc_set’)
make[3]: *** [scripts/Makefile.build:288: kernel/cgroup/rstat.o] Error 1
Please fix.
+};
+
+static int __init bpf_rstat_kfunc_init(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
+ &bpf_rstat_kfunc_set);
+}
+late_initcall(bpf_rstat_kfunc_init);
