net: filter: split 'struct sk_filter' into socket and bpf parts

clean up names related to socket filtering and bpf in the following way:
- everything that deals with sockets keeps 'sk_*' prefix
- everything that is pure BPF is changed to 'bpf_*' prefix

split 'struct sk_filter' into
struct sk_filter {
	atomic_t        refcnt;
	struct rcu_head rcu;
	struct bpf_prog *prog;
};
and
struct bpf_prog {
        u32                     jited:1,
                                len:31;
        struct sock_fprog_kern  *orig_prog;
        unsigned int            (*bpf_func)(const struct sk_buff *skb,
                                            const struct bpf_insn *filter);
        union {
                struct sock_filter      insns[0];
                struct bpf_insn         insnsi[0];
                struct work_struct      work;
        };
};
so that 'struct bpf_prog' can be used independent of sockets and cleans up
'unattached' bpf use cases

split SK_RUN_FILTER macro into:
    SK_RUN_FILTER to be used with 'struct sk_filter *' and
    BPF_PROG_RUN to be used with 'struct bpf_prog *'

__sk_filter_release(struct sk_filter *) gains
__bpf_prog_release(struct bpf_prog *) helper function

also perform related renames for the functions that work
with 'struct bpf_prog *', since they're on the same lines:

sk_filter_size -> bpf_prog_size
sk_filter_select_runtime -> bpf_prog_select_runtime
sk_filter_free -> bpf_prog_free
sk_unattached_filter_create -> bpf_prog_create
sk_unattached_filter_destroy -> bpf_prog_destroy
sk_store_orig_filter -> bpf_prog_store_orig_filter
sk_release_orig_filter -> bpf_release_orig_filter
__sk_migrate_filter -> bpf_migrate_filter
__sk_prepare_filter -> bpf_prepare_filter

API for attaching classic BPF to a socket stays the same:
sk_attach_filter(prog, struct sock *)/sk_detach_filter(struct sock *)
and SK_RUN_FILTER(struct sk_filter *, ctx) to execute a program
which is used by sockets, tun, af_packet

API for 'unattached' BPF programs becomes:
bpf_prog_create(struct bpf_prog **)/bpf_prog_destroy(struct bpf_prog *)
and BPF_PROG_RUN(struct bpf_prog *, ctx) to execute a program
which is used by isdn, ppp, team, seccomp, ptp, xt_bpf, cls_bpf, test_bpf

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/bpf/core.c

@@ -73,15 +73,13 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 }
 
 /**
- *	__sk_run_filter - run a filter on a given context
- *	@ctx: buffer to run the filter on
- *	@insn: filter to apply
+ *	__bpf_prog_run - run eBPF program on a given context
+ *	@ctx: is the data we are operating on
+ *	@insn: is the array of eBPF instructions
  *
- * Decode and apply filter instructions to the skb->data. Return length to
- * keep, 0 for none. @ctx is the data we are operating on, @insn is the
- * array of filter instructions.
+ * Decode and execute eBPF instructions.
  */
-static unsigned int __sk_run_filter(void *ctx, const struct bpf_insn *insn)
+static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
 {
 	u64 stack[MAX_BPF_STACK / sizeof(u64)];
 	u64 regs[MAX_BPF_REG], tmp;
@@ -508,29 +506,29 @@ load_byte:
 		return 0;
 }
 
-void __weak bpf_int_jit_compile(struct sk_filter *prog)
+void __weak bpf_int_jit_compile(struct bpf_prog *prog)
 {
 }
 
 /**
- *	sk_filter_select_runtime - select execution runtime for BPF program
- *	@fp: sk_filter populated with internal BPF program
+ *	bpf_prog_select_runtime - select execution runtime for BPF program
+ *	@fp: bpf_prog populated with internal BPF program
  *
  * try to JIT internal BPF program, if JIT is not available select interpreter
- * BPF program will be executed via SK_RUN_FILTER() macro
+ * BPF program will be executed via BPF_PROG_RUN() macro
  */
-void sk_filter_select_runtime(struct sk_filter *fp)
+void bpf_prog_select_runtime(struct bpf_prog *fp)
 {
-	fp->bpf_func = (void *) __sk_run_filter;
+	fp->bpf_func = (void *) __bpf_prog_run;
 
 	/* Probe if internal BPF can be JITed */
 	bpf_int_jit_compile(fp);
 }
-EXPORT_SYMBOL_GPL(sk_filter_select_runtime);
+EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);
 
 /* free internal BPF program */
-void sk_filter_free(struct sk_filter *fp)
+void bpf_prog_free(struct bpf_prog *fp)
 {
 	bpf_jit_free(fp);
 }
-EXPORT_SYMBOL_GPL(sk_filter_free);
+EXPORT_SYMBOL_GPL(bpf_prog_free);