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From:   Roman Gushchin <guro@fb.com>
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        Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH bpf-next 03/14] bpf: pass a pointer to a cgroup storage using pcpu variable
Date:   Thu, 28 Jun 2018 09:47:08 -0700
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This commit introduces the bpf_cgroup_storage_set() helper,
which will be used to pass a pointer to a cgroup storage
to the bpf helper.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 include/linux/bpf-cgroup.h | 14 ++++++++++++++
 kernel/bpf/local_storage.c |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index b4e2e42c1d2a..128fb0e39b4d 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -20,6 +20,8 @@ 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);
+
 struct bpf_cgroup_storage_map;
 
 struct bpf_storage_buffer {
@@ -96,6 +98,17 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
 int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 				      short access, enum bpf_attach_type type);
 
+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage)
+{
+	struct bpf_storage_buffer *buf;
+
+	if (!storage)
+		return;
+
+	buf = rcu_dereference(storage->buf);
+	this_cpu_write(bpf_cgroup_storage, &buf->data[0]);
+}
+
 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog);
 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage);
 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
@@ -223,6 +236,7 @@ struct cgroup_bpf {};
 static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
 static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
 
+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage) {}
 static inline int bpf_cgroup_storage_assign(struct bpf_prog *prog,
 					    struct bpf_map *map) { return 0; }
 static inline void bpf_cgroup_storage_release(struct bpf_prog *prog,
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 940889eda2c7..38810a712971 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -7,6 +7,8 @@
 #include <linux/rbtree.h>
 #include <linux/slab.h>
 
+DEFINE_PER_CPU(void*, bpf_cgroup_storage);
+
 #ifdef CONFIG_CGROUP_BPF
 
 struct bpf_cgroup_storage_map {
-- 
2.14.4