bpf: Move bpf_free_used_maps into sleepable section

We later on are going to need a sleepable context as opposed to plain
RCU callback in order to untrack programs we need to poke at runtime
and tracking as well as image update is performed under mutex.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/09823b1d5262876e9b83a8e75df04cf0467357a4.1574452833.git.daniel@iogearbox.net

include/linux/bpf.h

@@ -1031,6 +1031,10 @@ static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 {
 	return -ENOTSUPP;
 }
+
+static inline void bpf_map_put(struct bpf_map *map)
+{
+}
 #endif /* CONFIG_BPF_SYSCALL */
 
 static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,

kernel/bpf/core.c

@@ -2003,12 +2003,35 @@ int bpf_prog_array_copy_info(struct bpf_prog_array *array,
 								     : 0;
 }
 
+static void bpf_free_cgroup_storage(struct bpf_prog_aux *aux)
+{
+	enum bpf_cgroup_storage_type stype;
+
+	for_each_cgroup_storage_type(stype) {
+		if (!aux->cgroup_storage[stype])
+			continue;
+		bpf_cgroup_storage_release(aux->prog,
+					   aux->cgroup_storage[stype]);
+	}
+}
+
+static void bpf_free_used_maps(struct bpf_prog_aux *aux)
+{
+	int i;
+
+	bpf_free_cgroup_storage(aux);
+	for (i = 0; i < aux->used_map_cnt; i++)
+		bpf_map_put(aux->used_maps[i]);
+	kfree(aux->used_maps);
+}
+
 static void bpf_prog_free_deferred(struct work_struct *work)
 {
 	struct bpf_prog_aux *aux;
 	int i;
 
 	aux = container_of(work, struct bpf_prog_aux, work);
+	bpf_free_used_maps(aux);
 	if (bpf_prog_is_dev_bound(aux))
 		bpf_prog_offload_destroy(aux->prog);
 #ifdef CONFIG_PERF_EVENTS

kernel/bpf/syscall.c

@@ -1302,25 +1302,6 @@ static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 	return 0;
 }
 
-/* drop refcnt on maps used by eBPF program and free auxilary data */
-static void free_used_maps(struct bpf_prog_aux *aux)
-{
-	enum bpf_cgroup_storage_type stype;
-	int i;
-
-	for_each_cgroup_storage_type(stype) {
-		if (!aux->cgroup_storage[stype])
-			continue;
-		bpf_cgroup_storage_release(aux->prog,
-					   aux->cgroup_storage[stype]);
-	}
-
-	for (i = 0; i < aux->used_map_cnt; i++)
-		bpf_map_put(aux->used_maps[i]);
-
-	kfree(aux->used_maps);
-}
-
 int __bpf_prog_charge(struct user_struct *user, u32 pages)
 {
 	unsigned long memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
@@ -1415,7 +1396,6 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
 
 	kvfree(aux->func_info);
 	kfree(aux->func_info_aux);
-	free_used_maps(aux);
 	bpf_prog_uncharge_memlock(aux->prog);
 	security_bpf_prog_free(aux);
 	bpf_prog_free(aux->prog);