bpf: rework cgroup storage pointer passing

To simplify the following introduction of per-cpu cgroup storage,
let's rework a bit a mechanism of passing a pointer to a cgroup
storage into the bpf_get_local_storage(). Let's save a pointer
to the corresponding bpf_cgroup_storage structure, instead of
a pointer to the actual buffer.

It will help us to handle per-cpu storage later, which has
a different way of accessing to the actual data.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

3 files changed, 12 insertions, 12 deletions

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index e9871b012dac..7e0c9a1d48b7 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -23,7 +23,8 @@ struct bpf_cgroup_storage;
 extern struct static_key_false cgroup_bpf_enabled_key;
 #define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)
 
-DECLARE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
+DECLARE_PER_CPU(struct bpf_cgroup_storage*,
+                bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 #define for_each_cgroup_storage_type(stype) \
         for (stype = 0; stype < MAX_BPF_CGROUP_STORAGE_TYPE; stype++)
@@ -115,15 +116,9 @@ static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage
                                           *storage[MAX_BPF_CGROUP_STORAGE_TYPE])
 {
         enum bpf_cgroup_storage_type stype;
-        struct bpf_storage_buffer *buf;
-
-        for_each_cgroup_storage_type(stype) {
-                if (!storage[stype])
-                        continue;
 
-                buf = READ_ONCE(storage[stype]->buf);
-                this_cpu_write(bpf_cgroup_storage[stype], &buf->data[0]);
-        }
+        for_each_cgroup_storage_type(stype)
+                this_cpu_write(bpf_cgroup_storage[stype], storage[stype]);
 }
 
 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9070b2ace6aa..e42f8789b7ea 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -195,7 +195,8 @@ const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {
 };
 
 #ifdef CONFIG_CGROUP_BPF
-DECLARE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
+DECLARE_PER_CPU(struct bpf_cgroup_storage*,
+                bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
 {
@@ -204,8 +205,11 @@ BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
          * verifier checks that its value is correct.
          */
         enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
+        struct bpf_cgroup_storage *storage;
 
-        return (unsigned long) this_cpu_read(bpf_cgroup_storage[stype]);
+        storage = this_cpu_read(bpf_cgroup_storage[stype]);
+
+        return (unsigned long)&READ_ONCE(storage->buf)->data[0];
 }
 
 const struct bpf_func_proto bpf_get_local_storage_proto = {
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 0bd9f19fc557..6742292fb39e 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -7,7 +7,8 @@
 #include <linux/rbtree.h>
 #include <linux/slab.h>
 
-DEFINE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
+DEFINE_PER_CPU(struct bpf_cgroup_storage*,
+               bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 #ifdef CONFIG_CGROUP_BPF