bpf: Refactor bpf_iter_reg to have separate seq_info member

There is no functionality change for this patch.
Struct bpf_iter_reg is used to register a bpf_iter target,
which includes information for both prog_load, link_create
and seq_file creation.

This patch puts fields related seq_file creation into
a different structure. This will be useful for map
elements iterator where one iterator covers different
map types and different map types may have different
seq_ops, init/fini private_data function and
private_data size.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184109.590030-1-yhs@fb.com

include/linux/bpf.h

@@ -37,6 +37,15 @@ struct seq_operations;
 extern struct idr btf_idr;
 extern spinlock_t btf_idr_lock;
 
+typedef int (*bpf_iter_init_seq_priv_t)(void *private_data);
+typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
+struct bpf_iter_seq_info {
+	const struct seq_operations *seq_ops;
+	bpf_iter_init_seq_priv_t init_seq_private;
+	bpf_iter_fini_seq_priv_t fini_seq_private;
+	u32 seq_priv_size;
+};
+
 /* map is generic key/value storage optionally accesible by eBPF programs */
 struct bpf_map_ops {
 	/* funcs callable from userspace (via syscall) */
@@ -1189,18 +1198,12 @@ int bpf_obj_get_user(const char __user *pathname, int flags);
 	extern int bpf_iter_ ## target(args);			\
 	int __init bpf_iter_ ## target(args) { return 0; }
 
-typedef int (*bpf_iter_init_seq_priv_t)(void *private_data);
-typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
-
 #define BPF_ITER_CTX_ARG_MAX 2
 struct bpf_iter_reg {
 	const char *target;
-	const struct seq_operations *seq_ops;
-	bpf_iter_init_seq_priv_t init_seq_private;
-	bpf_iter_fini_seq_priv_t fini_seq_private;
-	u32 seq_priv_size;
 	u32 ctx_arg_info_size;
 	struct bpf_ctx_arg_aux ctx_arg_info[BPF_ITER_CTX_ARG_MAX];
+	const struct bpf_iter_seq_info *seq_info;
 };
 
 struct bpf_iter_meta {

kernel/bpf/bpf_iter.c

@@ -218,8 +218,8 @@ static int iter_release(struct inode *inode, struct file *file)
 	iter_priv = container_of(seq->private, struct bpf_iter_priv_data,
 				 target_private);
 
-	if (iter_priv->tinfo->reg_info->fini_seq_private)
-		iter_priv->tinfo->reg_info->fini_seq_private(seq->private);
+	if (iter_priv->tinfo->reg_info->seq_info->fini_seq_private)
+		iter_priv->tinfo->reg_info->seq_info->fini_seq_private(seq->private);
 
 	bpf_prog_put(iter_priv->prog);
 	seq->private = iter_priv;
@@ -433,16 +433,16 @@ static int prepare_seq_file(struct file *file, struct bpf_iter_link *link)
 
 	tinfo = link->tinfo;
 	total_priv_dsize = offsetof(struct bpf_iter_priv_data, target_private) +
-			   tinfo->reg_info->seq_priv_size;
-	priv_data = __seq_open_private(file, tinfo->reg_info->seq_ops,
+			   tinfo->reg_info->seq_info->seq_priv_size;
+	priv_data = __seq_open_private(file, tinfo->reg_info->seq_info->seq_ops,
 				       total_priv_dsize);
 	if (!priv_data) {
 		err = -ENOMEM;
 		goto release_prog;
 	}
 
-	if (tinfo->reg_info->init_seq_private) {
-		err = tinfo->reg_info->init_seq_private(priv_data->target_private);
+	if (tinfo->reg_info->seq_info->init_seq_private) {
+		err = tinfo->reg_info->seq_info->init_seq_private(priv_data->target_private);
 		if (err)
 			goto release_seq_file;
 	}

kernel/bpf/map_iter.c

@@ -81,17 +81,21 @@ static const struct seq_operations bpf_map_seq_ops = {
 BTF_ID_LIST(btf_bpf_map_id)
 BTF_ID(struct, bpf_map)
 
-static struct bpf_iter_reg bpf_map_reg_info = {
-	.target			= "bpf_map",
+static const struct bpf_iter_seq_info bpf_map_seq_info = {
 	.seq_ops		= &bpf_map_seq_ops,
 	.init_seq_private	= NULL,
 	.fini_seq_private	= NULL,
 	.seq_priv_size		= sizeof(struct bpf_iter_seq_map_info),
+};
+
+static struct bpf_iter_reg bpf_map_reg_info = {
+	.target			= "bpf_map",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__bpf_map, map),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &bpf_map_seq_info,
 };
 
 static int __init bpf_map_iter_init(void)

kernel/bpf/prog_iter.c

@@ -81,17 +81,21 @@ static const struct seq_operations bpf_prog_seq_ops = {
 BTF_ID_LIST(btf_bpf_prog_id)
 BTF_ID(struct, bpf_prog)
 
-static struct bpf_iter_reg bpf_prog_reg_info = {
-	.target			= "bpf_prog",
+static const struct bpf_iter_seq_info bpf_prog_seq_info = {
 	.seq_ops		= &bpf_prog_seq_ops,
 	.init_seq_private	= NULL,
 	.fini_seq_private	= NULL,
 	.seq_priv_size		= sizeof(struct bpf_iter_seq_prog_info),
+};
+
+static struct bpf_iter_reg bpf_prog_reg_info = {
+	.target			= "bpf_prog",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__bpf_prog, prog),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &bpf_prog_seq_info,
 };
 
 static int __init bpf_prog_iter_init(void)

kernel/bpf/task_iter.c

@@ -319,32 +319,40 @@ BTF_ID_LIST(btf_task_file_ids)
 BTF_ID(struct, task_struct)
 BTF_ID(struct, file)
 
-static struct bpf_iter_reg task_reg_info = {
-	.target			= "task",
+static const struct bpf_iter_seq_info task_seq_info = {
 	.seq_ops		= &task_seq_ops,
 	.init_seq_private	= init_seq_pidns,
 	.fini_seq_private	= fini_seq_pidns,
 	.seq_priv_size		= sizeof(struct bpf_iter_seq_task_info),
+};
+
+static struct bpf_iter_reg task_reg_info = {
+	.target			= "task",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__task, task),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &task_seq_info,
 };
 
-static struct bpf_iter_reg task_file_reg_info = {
-	.target			= "task_file",
+static const struct bpf_iter_seq_info task_file_seq_info = {
 	.seq_ops		= &task_file_seq_ops,
 	.init_seq_private	= init_seq_pidns,
 	.fini_seq_private	= fini_seq_pidns,
 	.seq_priv_size		= sizeof(struct bpf_iter_seq_task_file_info),
+};
+
+static struct bpf_iter_reg task_file_reg_info = {
+	.target			= "task_file",
 	.ctx_arg_info_size	= 2,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__task_file, task),
 		  PTR_TO_BTF_ID_OR_NULL },
 		{ offsetof(struct bpf_iter__task_file, file),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &task_file_seq_info,
 };
 
 static int __init task_iter_init(void)

net/ipv4/tcp_ipv4.c

@@ -2947,17 +2947,21 @@ static void bpf_iter_fini_tcp(void *priv_data)
 	bpf_iter_fini_seq_net(priv_data);
 }
 
-static struct bpf_iter_reg tcp_reg_info = {
-	.target			= "tcp",
+static const struct bpf_iter_seq_info tcp_seq_info = {
 	.seq_ops		= &bpf_iter_tcp_seq_ops,
 	.init_seq_private	= bpf_iter_init_tcp,
 	.fini_seq_private	= bpf_iter_fini_tcp,
 	.seq_priv_size		= sizeof(struct tcp_iter_state),
+};
+
+static struct bpf_iter_reg tcp_reg_info = {
+	.target			= "tcp",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__tcp, sk_common),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &tcp_seq_info,
 };
 
 static void __init bpf_iter_register(void)

net/ipv4/udp.c

@@ -3208,17 +3208,21 @@ static void bpf_iter_fini_udp(void *priv_data)
 	bpf_iter_fini_seq_net(priv_data);
 }
 
-static struct bpf_iter_reg udp_reg_info = {
-	.target			= "udp",
+static const struct bpf_iter_seq_info udp_seq_info = {
 	.seq_ops		= &bpf_iter_udp_seq_ops,
 	.init_seq_private	= bpf_iter_init_udp,
 	.fini_seq_private	= bpf_iter_fini_udp,
 	.seq_priv_size		= sizeof(struct udp_iter_state),
+};
+
+static struct bpf_iter_reg udp_reg_info = {
+	.target			= "udp",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__udp, udp_sk),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &udp_seq_info,
 };
 
 static void __init bpf_iter_register(void)

net/ipv6/route.c

@@ -6427,17 +6427,21 @@ DEFINE_BPF_ITER_FUNC(ipv6_route, struct bpf_iter_meta *meta, struct fib6_info *r
 BTF_ID_LIST(btf_fib6_info_id)
 BTF_ID(struct, fib6_info)
 
-static struct bpf_iter_reg ipv6_route_reg_info = {
-	.target			= "ipv6_route",
+static const struct bpf_iter_seq_info ipv6_route_seq_info = {
 	.seq_ops		= &ipv6_route_seq_ops,
 	.init_seq_private	= bpf_iter_init_seq_net,
 	.fini_seq_private	= bpf_iter_fini_seq_net,
 	.seq_priv_size		= sizeof(struct ipv6_route_iter),
+};
+
+static struct bpf_iter_reg ipv6_route_reg_info = {
+	.target			= "ipv6_route",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__ipv6_route, rt),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &ipv6_route_seq_info,
 };
 
 static int __init bpf_iter_register(void)

net/netlink/af_netlink.c

@@ -2807,17 +2807,21 @@ static const struct rhashtable_params netlink_rhashtable_params = {
 BTF_ID_LIST(btf_netlink_sock_id)
 BTF_ID(struct, netlink_sock)
 
-static struct bpf_iter_reg netlink_reg_info = {
-	.target			= "netlink",
+static const struct bpf_iter_seq_info netlink_seq_info = {
 	.seq_ops		= &netlink_seq_ops,
 	.init_seq_private	= bpf_iter_init_seq_net,
 	.fini_seq_private	= bpf_iter_fini_seq_net,
 	.seq_priv_size		= sizeof(struct nl_seq_iter),
+};
+
+static struct bpf_iter_reg netlink_reg_info = {
+	.target			= "netlink",
 	.ctx_arg_info_size	= 1,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__netlink, sk),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
+	.seq_info		= &netlink_seq_info,
 };
 
 static int __init bpf_iter_register(void)