From: Brenden Blanco <bbla...@plumgrid.com>
Date: Mon, 11 Jul 2016 23:35:00 -0700
> On Mon, Jul 11, 2016 at 11:12:24PM -0700, David Miller wrote:
>> From: Brenden Blanco <bbla...@plumgrid.com>
>> Date: Mon, 11 Jul 2016 14:29:49 -0700
>>
>> > + if (fd >= 0) {
>> > + prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
>> > + if (IS_ERR(prog))
>> > + return PTR_ERR(prog);
>> > + }
>> > +
>> > + xdp.command = XDP_SETUP_PROG;
>> > + xdp.prog = prog;
>> > + err = ops->ndo_xdp(dev, &xdp);
>> > + if (err < 0 && prog)
>> > + bpf_prog_put(prog);
>>
>> I don't understand the reference counting on 'prog' here.
>>
>> The enumeration documentation states that no matter what, the passed
>> in prog doesn't need to be mangaged by the ->ndo_xdp() method.
>>
>> Therefore, if that is true, we must always put the 'prog' here if it
>> is non-NULL. Regardless of the 'err' value.
>>
> The documentation is unclear then. What I _meant_ to say is that the callee
> is not responsible for putting the program on error, but on success it
> takes ownership of the reference. In context of that, does the code make
> sense? Is there a more conventional way of handling this?
Then please document it more clearly, thanks.
