From: Brenden Blanco <bblanco@plumgrid.com>
Date: Tue, 19 Jul 2016 19:16:46 +0000 (-0700)
Subject: bpf: add bpf_prog_add api for bulk prog refcnt
X-Git-Tag: v4.8-rc1~140^2~64^2~11
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=59d3656d5bf50;p=karo-tx-linux.git

bpf: add bpf_prog_add api for bulk prog refcnt

A subsystem may need to store many copies of a bpf program, each
deserving its own reference. Rather than requiring the caller to loop
one by one (with possible mid-loop failure), add a bulk bpf_prog_add
api.

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c13e92b00bf5..75a5ae6bee07 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -224,6 +224,7 @@ void bpf_register_map_type(struct bpf_map_type_list *tl);
 
 struct bpf_prog *bpf_prog_get(u32 ufd);
 struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
+struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i);
 struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog);
 void bpf_prog_put(struct bpf_prog *prog);
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 96d938a22050..228f962447a5 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -670,14 +670,20 @@ static struct bpf_prog *____bpf_prog_get(struct fd f)
 	return f.file->private_data;
 }
 
-struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
+struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i)
 {
-	if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) {
-		atomic_dec(&prog->aux->refcnt);
+	if (atomic_add_return(i, &prog->aux->refcnt) > BPF_MAX_REFCNT) {
+		atomic_sub(i, &prog->aux->refcnt);
 		return ERR_PTR(-EBUSY);
 	}
 	return prog;
 }
+EXPORT_SYMBOL_GPL(bpf_prog_add);
+
+struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
+{
+	return bpf_prog_add(prog, 1);
+}
 
 static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
 {