netdev - Re: [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG

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Message-ID: <1473096597.1992.2.camel@perches.com>
Date:   Mon, 05 Sep 2016 10:29:57 -0700
From:   Joe Perches <joe@...ches.com>
To:     Daniel Mack <daniel@...que.org>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     htejun@...com, daniel@...earbox.net, ast@...com,
        davem@...emloft.net, kafai@...com, fw@...len.de,
        pablo@...filter.org, harald@...hat.com, netdev@...r.kernel.org,
        sargun@...gun.me
Subject: Re: [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH
 commands

On Mon, 2016-09-05 at 14:56 +0200, Daniel Mack wrote:
> On 08/27/2016 02:08 AM, Alexei Starovoitov wrote:
[]
> > +	switch (attr->attach_type) {
> > +	case BPF_ATTACH_TYPE_CGROUP_INET_INGRESS:
> > +	case BPF_ATTACH_TYPE_CGROUP_INET_EGRESS: {
> > +		struct cgroup *cgrp;
> > +
> > +		prog = bpf_prog_get_type(attr->attach_bpf_fd,
> > +					 BPF_PROG_TYPE_CGROUP_SOCKET_FILTER);
> > +		if (IS_ERR(prog))
> > +			return PTR_ERR(prog);
> > +
> > +		cgrp = cgroup_get_from_fd(attr->target_fd);
> > +		if (IS_ERR(cgrp)) {
> > +			bpf_prog_put(prog);
> > +			return PTR_ERR(cgrp);
> > +		}
> > +
> > +		cgroup_bpf_update(cgrp, prog, attr->attach_type);
> > +		cgroup_put(cgrp);
> > +
> > +		break;
> > +	}
> this } formatting style is confusing. The above } looks
> like it matches 'switch () {'.
> May be move 'struct cgroup *cgrp' to the top to avoid that?

This style of case statements that declare local variables
with an open brace after the case statement

	switch (bar) {
	[cases...]
	case foo: {
		local declarations;

		code...
	}
	[cases...]
	}

is used quite frequently in the kernel.
I think it's fine as is.