Re: [PATCH v2 net-next 8/9] bpf: nfp: Report bpf_prog ID during XDP_QUERY_PROG

On Tue, 13 Jun 2017 20:19:53 -0700, Martin KaFai Lau wrote:

On Tue, Jun 13, 2017 at 07:19:50PM -0700, Jakub Kicinski wrote:

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On Tue, 13 Jun 2017 17:37:50 -0700, Martin KaFai Lau wrote:  

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On Tue, Jun 13, 2017 at 04:52:32PM -0700, Jakub Kicinski wrote:  

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On Tue, 13 Jun 2017 14:08:40 -0700, Martin KaFai Lau wrote:  

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-	case XDP_QUERY_PROG:
-		xdp->prog_attached = !!nn->dp.xdp_prog;
+	case XDP_QUERY_PROG: {
+		const struct bpf_prog *xdp_prog;
+
+		xdp_prog = nn->dp.xdp_prog;
+		if (xdp_prog) {
+			xdp->prog_id = xdp_prog->aux->id;
+			xdp->prog_attached = true;
+		} else {
+			xdp->prog_id = 0;
+			xdp->prog_attached = false;
+		}
 		return 0;
+	}  

I'm sorry to nit pick but it could be done on a single line:

	case XDP_QUERY_PROG:
		xdp->prog_attached = !!nn->dp.xdp_prog;
+		xdp->prog_id = nn->dp.xdp_prog ? nn->dp.xdp_prog->aux->id : 0;
 		return 0;
 	default:
 		return -EINVAL;  

OK...
 

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What would be even cooler is a helper like this:

static inline u32 bpf_prog_id(struct bpf_prog *prog)
{
	if (!prog)
		return 0;
	return prog->aux->id;
}

in linux/bpf.h.  

Good idea.  

You may actually have to add that into a source file, because bpf.h
does not know the definition of struct bpf_prog :(  

Yeah. filter.h seems not working well either.
It looks good to me at the first thought.  After a second thought,
in the future, I am not so sure having a getter for every fields
in bpf_prog.

Yes, if it's not a static inline it's far less appealing...
 

I can put bpf_prog_id() in nfp_net_common.c only.
or do 'xdp->prog_id = nn->dp.xdp_prog ? nn->dp.xdp_prog->aux->id : 0;'
as you suggested earlier also.
I am fine either way.  Your call ;)

OK, let's do the ternary operator version then :)  Sorry for leading you
into this dead end.