include/net/cls_cgroup.h

   1 /*
   2  * cls_cgroup.h                 Control Group Classifier
   3  *
   4  * Authors:     Thomas Graf <tgraf@suug.ch>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #ifndef _NET_CLS_CGROUP_H
  14 #define _NET_CLS_CGROUP_H
  15
  16 #include <linux/cgroup.h>
  17 #include <linux/hardirq.h>
  18 #include <linux/rcupdate.h>
  19 #include <net/sock.h>
  20
  21 #ifdef CONFIG_CGROUP_NET_CLASSID
  22 struct cgroup_cls_state {
  23         struct cgroup_subsys_state css;
  24         u32 classid;
  25 };
  26
  27 struct cgroup_cls_state *task_cls_state(struct task_struct *p);
  28
  29 static inline u32 task_cls_classid(struct task_struct *p)
  30 {
  31         u32 classid;
  32
  33         if (in_interrupt())
  34                 return 0;
  35
  36         rcu_read_lock();
  37         classid = container_of(task_css(p, net_cls_cgrp_id),
  38                                struct cgroup_cls_state, css)->classid;
  39         rcu_read_unlock();
  40
  41         return classid;
  42 }
  43
  44 static inline void sock_update_classid(struct sock *sk)
  45 {
  46         u32 classid;
  47
  48         classid = task_cls_classid(current);
  49         if (classid != sk->sk_classid)
  50                 sk->sk_classid = classid;
  51 }
  52
  53 static inline u32 task_get_classid(const struct sk_buff *skb)
  54 {
  55         u32 classid = task_cls_state(current)->classid;
  56
  57         /* Due to the nature of the classifier it is required to ignore all
  58          * packets originating from softirq context as accessing `current'
  59          * would lead to false results.
  60          *
  61          * This test assumes that all callers of dev_queue_xmit() explicitly
  62          * disable bh. Knowing this, it is possible to detect softirq based
  63          * calls by looking at the number of nested bh disable calls because
  64          * softirqs always disables bh.
  65          */
  66         if (in_serving_softirq()) {
  67                 /* If there is an sk_classid we'll use that. */
  68                 if (!skb->sk)
  69                         return 0;
  70
  71                 classid = skb->sk->sk_classid;
  72         }
  73
  74         return classid;
  75 }
  76 #else /* !CONFIG_CGROUP_NET_CLASSID */
  77 static inline void sock_update_classid(struct sock *sk)
  78 {
  79 }
  80
  81 static inline u32 task_get_classid(const struct sk_buff *skb)
  82 {
  83         return 0;
  84 }
  85 #endif /* CONFIG_CGROUP_NET_CLASSID */
  86 #endif  /* _NET_CLS_CGROUP_H */