On 12/15/21 16:40, Jakub Kicinski wrote:
On Wed, 15 Dec 2021 14:49:18 +0000 Pavel Begunkov wrote:
+static inline bool
+__cgroup_bpf_prog_array_is_empty(struct cgroup_bpf *cgrp_bpf,
+ enum cgroup_bpf_attach_type type)
+{
+ struct bpf_prog_array *array = rcu_access_pointer(cgrp_bpf->effective[type]);
+
+ return array == &bpf_empty_prog_array.hdr;
+}
+
+#define CGROUP_BPF_TYPE_ENABLED(sk, atype) \
+({ \
+ struct cgroup *__cgrp = sock_cgroup_ptr(&(sk)->sk_cgrp_data); \
+ \
+ !__cgroup_bpf_prog_array_is_empty(&__cgrp->bpf, (atype)); \
+})
+
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e7a163a3146b..0d2195c6fb2a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1161,6 +1161,19 @@ struct bpf_prog_array {
struct bpf_prog_array_item items[];
};
+struct bpf_empty_prog_array {
+ struct bpf_prog_array hdr;
+ struct bpf_prog *null_prog;
+};
+
+/* to avoid allocating empty bpf_prog_array for cgroups that
+ * don't have bpf program attached use one global 'bpf_empty_prog_array'
+ * It will not be modified the caller of bpf_prog_array_alloc()
+ * (since caller requested prog_cnt == 0)
+ * that pointer should be 'freed' by bpf_prog_array_free()
+ */
+extern struct bpf_empty_prog_array bpf_empty_prog_array;
mumble mumble, this adds more "fun" dependencies [1] Maybe I'm going
Header dependencies? It's declared right after struct bpf_prog_array,
and the other member is a pointer, so not sure what can go wrong.
about this all wrong, maybe I should be pulling out struct cgroup_bpf
so that cgroup.h does not need bpf-cgroup, not breaking bpf <-> bpf-cgroup.
Alexei, WDYT?
[1] https://lore.kernel.org/all/20211215061916.715513-2-kuba@xxxxxxxxxx/
--
Pavel Begunkov
