Re: [PATCH bpf-next v8 04/10] bpf: hold module for bpf_struct_ops_map.

[Kui-Feng Lee <sinquersw@xxxxxxxxx>]

On 10/30/23 18:21, Martin KaFai Lau wrote:
> On 10/30/23 12:28 PM, thinker.li@xxxxxxxxx wrote:
> > @@ -681,9 +697,17 @@ static struct bpf_map 
> > *bpf_struct_ops_map_alloc(union bpf_attr *attr)
> >       if (!st_ops_desc)
> >           return ERR_PTR(-ENOTSUPP);
> > +    if (st_ops_desc->btf != btf_vmlinux) {
> > +        mod = btf_try_get_module(st_ops_desc->btf);
> > +        if (!mod)
> > +            return ERR_PTR(-EINVAL);
> > +    }
> > +
> >       vt = st_ops_desc->value_type;
> > -    if (attr->value_size != vt->size)
> > -        return ERR_PTR(-EINVAL);
> > +    if (attr->value_size != vt->size) {
> > +        ret = -EINVAL;
> > +        goto errout;
> > +    }
> >       t = st_ops_desc->type;
> > @@ -694,17 +718,17 @@ static struct bpf_map 
> > *bpf_struct_ops_map_alloc(union bpf_attr *attr)
> >           (vt->size - sizeof(struct bpf_struct_ops_value));
> >       st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE);
> > -    if (!st_map)
> > -        return ERR_PTR(-ENOMEM);
> > +    if (!st_map) {
> > +        ret = -ENOMEM;
> > +        goto errout;
> > +    }
> >       st_map->st_ops_desc = st_ops_desc;
> >       map = &st_map->map;
> >       ret = bpf_jit_charge_modmem(PAGE_SIZE);
> > -    if (ret) {
> > -        __bpf_struct_ops_map_free(map);
> > -        return ERR_PTR(ret);
> > -    }
> > +    if (ret)
> > +        goto errout_free;
> >       st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
> >       if (!st_map->image) {
> > @@ -713,23 +737,32 @@ static struct bpf_map 
> > *bpf_struct_ops_map_alloc(union bpf_attr *attr)
> >            * here.
> >            */
> >           bpf_jit_uncharge_modmem(PAGE_SIZE);
> > -        __bpf_struct_ops_map_free(map);
> > -        return ERR_PTR(-ENOMEM);
> > +        ret = -ENOMEM;
> > +        goto errout_free;
> >       }
> >       st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
> >       st_map->links =
> >           bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct 
> > bpf_links *),
> >                      NUMA_NO_NODE);
> >       if (!st_map->uvalue || !st_map->links) {
> > -        __bpf_struct_ops_map_free(map);
> > -        return ERR_PTR(-ENOMEM);
> > +        ret = -ENOMEM;
> > +        goto errout_free;
> >       }
> >       mutex_init(&st_map->lock);
> >       set_vm_flush_reset_perms(st_map->image);
> >       bpf_map_init_from_attr(map, attr);
> > +    module_put(mod);
> > +
> >       return map;
> > +
> > +errout_free:
> > +    __bpf_struct_ops_map_free(map);
> > +    btf = NULL;        /* has been released */
>
> btf is not defined. I don't think this patch compiles.
> Something from a latter patch?

Yes, it is defined in the next patch. I will fix it.

> > +errout:
> > +    module_put(mod);
> > +    return ERR_PTR(ret);
> >   }