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bpf: add bpf_prog_add api for bulk prog refcnt

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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>
This commit is contained in:
Brenden Blanco 2016-07-19 12:16:46 -07:00 committed by David S. Miller
parent ddbcb79493
commit 59d3656d5b
2 changed files with 10 additions and 3 deletions
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1
include/linux/bpf.h
View file

@ -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);

12
kernel/bpf/syscall.c
View file

@ -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)
{