netdev - [PATCH v4 bpf-next 1/6] bpf: Define cgroup_bpf_enabled for CONFIG_CGROUP

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Date:   Fri, 25 May 2018 08:55:22 -0700
From:   Andrey Ignatov <rdna@...com>
To:     <netdev@...r.kernel.org>
CC:     Andrey Ignatov <rdna@...com>, <davem@...emloft.net>,
        <kafai@...com>, <ast@...nel.org>, <daniel@...earbox.net>,
        <kernel-team@...com>
Subject: [PATCH v4 bpf-next 1/6] bpf: Define cgroup_bpf_enabled for CONFIG_CGROUP_BPF=n

Static key is used to enable/disable cgroup-bpf related code paths at
run time.

Though it's not defined when cgroup-bpf is disabled at compile time,
i.e. CONFIG_CGROUP_BPF=n, and if some code wants to use it, it has to do
this:

	#ifdef CONFIG_CGROUP_BPF
		if (cgroup_bpf_enabled) {
			/* ... some work ... */
		}
	#endif

This code can be simplified by setting cgroup_bpf_enabled to 0 for
CONFIG_CGROUP_BPF=n case:

	if (cgroup_bpf_enabled) {
		/* ... some work ... */
	}

And it aligns well with existing BPF_CGROUP_RUN_PROG_* macros that
defined for both states of CONFIG_CGROUP_BPF.

Signed-off-by: Andrey Ignatov <rdna@...com>
---
 include/linux/bpf-cgroup.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 30d15e6..de8e89a 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -185,6 +185,7 @@ struct cgroup_bpf {};
 static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
 static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
 
+#define cgroup_bpf_enabled (0)
 #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
 #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })
-- 
2.9.5