bpf: Remove the cgroup -> bpf header dependecy

Remove the dependency from cgroup-defs.h to bpf-cgroup.h and bpf.h.
This reduces the incremental build size of x86 allmodconfig after
bpf.h was touched from ~17k objects rebuilt to ~5k objects.
bpf.h is 2.2kLoC and is modified relatively often.

We need a new header with just the definition of struct cgroup_bpf
and enum cgroup_bpf_attach_type, this is akin to cgroup-defs.h.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/bpf/20211216025538.1649516-4-kuba@kernel.org

include/linux/bpf-cgroup-defs.h

@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BPF_CGROUP_DEFS_H
+#define _BPF_CGROUP_DEFS_H
+
+#ifdef CONFIG_CGROUP_BPF
+
+#include <linux/list.h>
+#include <linux/percpu-refcount.h>
+#include <linux/workqueue.h>
+
+struct bpf_prog_array;
+
+enum cgroup_bpf_attach_type {
+	CGROUP_BPF_ATTACH_TYPE_INVALID = -1,
+	CGROUP_INET_INGRESS = 0,
+	CGROUP_INET_EGRESS,
+	CGROUP_INET_SOCK_CREATE,
+	CGROUP_SOCK_OPS,
+	CGROUP_DEVICE,
+	CGROUP_INET4_BIND,
+	CGROUP_INET6_BIND,
+	CGROUP_INET4_CONNECT,
+	CGROUP_INET6_CONNECT,
+	CGROUP_INET4_POST_BIND,
+	CGROUP_INET6_POST_BIND,
+	CGROUP_UDP4_SENDMSG,
+	CGROUP_UDP6_SENDMSG,
+	CGROUP_SYSCTL,
+	CGROUP_UDP4_RECVMSG,
+	CGROUP_UDP6_RECVMSG,
+	CGROUP_GETSOCKOPT,
+	CGROUP_SETSOCKOPT,
+	CGROUP_INET4_GETPEERNAME,
+	CGROUP_INET6_GETPEERNAME,
+	CGROUP_INET4_GETSOCKNAME,
+	CGROUP_INET6_GETSOCKNAME,
+	CGROUP_INET_SOCK_RELEASE,
+	MAX_CGROUP_BPF_ATTACH_TYPE
+};
+
+struct cgroup_bpf {
+	/* array of effective progs in this cgroup */
+	struct bpf_prog_array __rcu *effective[MAX_CGROUP_BPF_ATTACH_TYPE];
+
+	/* attached progs to this cgroup and attach flags
+	 * when flags == 0 or BPF_F_ALLOW_OVERRIDE the progs list will
+	 * have either zero or one element
+	 * when BPF_F_ALLOW_MULTI the list can have up to BPF_CGROUP_MAX_PROGS
+	 */
+	struct list_head progs[MAX_CGROUP_BPF_ATTACH_TYPE];
+	u32 flags[MAX_CGROUP_BPF_ATTACH_TYPE];
+
+	/* list of cgroup shared storages */
+	struct list_head storages;
+
+	/* temp storage for effective prog array used by prog_attach/detach */
+	struct bpf_prog_array *inactive;
+
+	/* reference counter used to detach bpf programs after cgroup removal */
+	struct percpu_ref refcnt;
+
+	/* cgroup_bpf is released using a work queue */
+	struct work_struct release_work;
+};
+
+#else /* CONFIG_CGROUP_BPF */
+struct cgroup_bpf {};
+#endif /* CONFIG_CGROUP_BPF */
+
+#endif

include/linux/bpf-cgroup.h

@@ -3,10 +3,10 @@
 #define _BPF_CGROUP_H
 
 #include <linux/bpf.h>
+#include <linux/bpf-cgroup-defs.h>
 #include <linux/errno.h>
 #include <linux/jump_label.h>
 #include <linux/percpu.h>
-#include <linux/percpu-refcount.h>
 #include <linux/rbtree.h>
 #include <uapi/linux/bpf.h>
 
@@ -23,33 +23,6 @@ struct ctl_table_header;
 struct task_struct;
 
 #ifdef CONFIG_CGROUP_BPF
-enum cgroup_bpf_attach_type {
-	CGROUP_BPF_ATTACH_TYPE_INVALID = -1,
-	CGROUP_INET_INGRESS = 0,
-	CGROUP_INET_EGRESS,
-	CGROUP_INET_SOCK_CREATE,
-	CGROUP_SOCK_OPS,
-	CGROUP_DEVICE,
-	CGROUP_INET4_BIND,
-	CGROUP_INET6_BIND,
-	CGROUP_INET4_CONNECT,
-	CGROUP_INET6_CONNECT,
-	CGROUP_INET4_POST_BIND,
-	CGROUP_INET6_POST_BIND,
-	CGROUP_UDP4_SENDMSG,
-	CGROUP_UDP6_SENDMSG,
-	CGROUP_SYSCTL,
-	CGROUP_UDP4_RECVMSG,
-	CGROUP_UDP6_RECVMSG,
-	CGROUP_GETSOCKOPT,
-	CGROUP_SETSOCKOPT,
-	CGROUP_INET4_GETPEERNAME,
-	CGROUP_INET6_GETPEERNAME,
-	CGROUP_INET4_GETSOCKNAME,
-	CGROUP_INET6_GETSOCKNAME,
-	CGROUP_INET_SOCK_RELEASE,
-	MAX_CGROUP_BPF_ATTACH_TYPE
-};
 
 #define CGROUP_ATYPE(type) \
 	case BPF_##type: return type
@@ -127,33 +100,6 @@ struct bpf_prog_list {
 	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE];
 };
 
-struct bpf_prog_array;
-
-struct cgroup_bpf {
-	/* array of effective progs in this cgroup */
-	struct bpf_prog_array __rcu *effective[MAX_CGROUP_BPF_ATTACH_TYPE];
-
-	/* attached progs to this cgroup and attach flags
-	 * when flags == 0 or BPF_F_ALLOW_OVERRIDE the progs list will
-	 * have either zero or one element
-	 * when BPF_F_ALLOW_MULTI the list can have up to BPF_CGROUP_MAX_PROGS
-	 */
-	struct list_head progs[MAX_CGROUP_BPF_ATTACH_TYPE];
-	u32 flags[MAX_CGROUP_BPF_ATTACH_TYPE];
-
-	/* list of cgroup shared storages */
-	struct list_head storages;
-
-	/* temp storage for effective prog array used by prog_attach/detach */
-	struct bpf_prog_array *inactive;
-
-	/* reference counter used to detach bpf programs after cgroup removal */
-	struct percpu_ref refcnt;
-
-	/* cgroup_bpf is released using a work queue */
-	struct work_struct release_work;
-};
-
 int cgroup_bpf_inherit(struct cgroup *cgrp);
 void cgroup_bpf_offline(struct cgroup *cgrp);
 
@@ -451,7 +397,6 @@ int cgroup_bpf_prog_query(const union bpf_attr *attr,
 			  union bpf_attr __user *uattr);
 #else
 
-struct cgroup_bpf {};
 static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
 static inline void cgroup_bpf_offline(struct cgroup *cgrp) {}
 

include/linux/cgroup-defs.h

@@ -19,7 +19,7 @@
 #include <linux/percpu-rwsem.h>
 #include <linux/u64_stats_sync.h>
 #include <linux/workqueue.h>
-#include <linux/bpf-cgroup.h>
+#include <linux/bpf-cgroup-defs.h>
 #include <linux/psi_types.h>
 
 #ifdef CONFIG_CGROUPS