sch_generic.h

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#ifndef __NET_SCHED_GENERIC_H
#define __NET_SCHED_GENERIC_H

#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/pkt_sched.h>
#include <linux/pkt_cls.h>
#include <net/gen_stats.h>
#include <net/rtnetlink.h>

struct Qdisc_ops;
struct qdisc_walker;
struct tcf_walker;
struct module;

struct qdisc_rate_table {
    struct tc_ratespec rate;
    u32     data[256];
    struct qdisc_rate_table *next;
    int     refcnt;
};

enum qdisc_state_t {
    __QDISC_STATE_SCHED,
    __QDISC_STATE_DEACTIVATED,
    __QDISC_STATE_THROTTLED,
};

/*
 * following bits are only changed while qdisc lock is held
 */
enum qdisc___state_t {
    __QDISC___STATE_RUNNING = 1,
};

struct qdisc_size_table {
    struct rcu_head     rcu;
    struct list_head    list;
    struct tc_sizespec  szopts;
    int         refcnt;
    u16         data[];
};

struct Qdisc {
    int             (*enqueue)(struct sk_buff *skb, struct Qdisc *dev);
    struct sk_buff *    (*dequeue)(struct Qdisc *dev);
    unsigned int        flags;
#define TCQ_F_BUILTIN       1
#define TCQ_F_INGRESS       2
#define TCQ_F_CAN_BYPASS    4
#define TCQ_F_MQROOT        8
#define TCQ_F_WARN_NONWC    (1 << 16)
    int         padded;
    const struct Qdisc_ops  *ops;
    struct qdisc_size_table __rcu *stab;
    struct list_head    list;
    u32         handle;
    u32         parent;
    atomic_t        refcnt;
    struct gnet_stats_rate_est  rate_est;
    int         (*reshape_fail)(struct sk_buff *skb,
                    struct Qdisc *q);

    void            *u32_node;

    /* This field is deprecated, but it is still used by CBQ
     * and it will live until better solution will be invented.
     */
    struct Qdisc        *__parent;
    struct netdev_queue *dev_queue;
    struct Qdisc        *next_sched;

    struct sk_buff      *gso_skb;
    /*
     * For performance sake on SMP, we put highly modified fields at the end
     */
    unsigned long       state;
    struct sk_buff_head q;
    struct gnet_stats_basic_packed bstats;
    unsigned int        __state;
    struct gnet_stats_queue qstats;
    struct rcu_head     rcu_head;
    spinlock_t      busylock;
    u32         limit;
};

static inline bool qdisc_is_running(const struct Qdisc *qdisc)
{
    return (qdisc->__state & __QDISC___STATE_RUNNING) ? true : false;
}

static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
    if (qdisc_is_running(qdisc))
        return false;
    qdisc->__state |= __QDISC___STATE_RUNNING;
    return true;
}

static inline void qdisc_run_end(struct Qdisc *qdisc)
{
    qdisc->__state &= ~__QDISC___STATE_RUNNING;
}

static inline bool qdisc_is_throttled(const struct Qdisc *qdisc)
{
    return test_bit(__QDISC_STATE_THROTTLED, &qdisc->state) ? true : false;
}

static inline void qdisc_throttled(struct Qdisc *qdisc)
{
    set_bit(__QDISC_STATE_THROTTLED, &qdisc->state);
}

static inline void qdisc_unthrottled(struct Qdisc *qdisc)
{
    clear_bit(__QDISC_STATE_THROTTLED, &qdisc->state);
}

struct Qdisc_class_ops {
    /* Child qdisc manipulation */
    struct netdev_queue *   (*select_queue)(struct Qdisc *, struct tcmsg *);
    int         (*graft)(struct Qdisc *, unsigned long cl,
                    struct Qdisc *, struct Qdisc **);
    struct Qdisc *      (*leaf)(struct Qdisc *, unsigned long cl);
    void            (*qlen_notify)(struct Qdisc *, unsigned long);

    /* Class manipulation routines */
    unsigned long       (*get)(struct Qdisc *, u32 classid);
    void            (*put)(struct Qdisc *, unsigned long);
    int         (*change)(struct Qdisc *, u32, u32,
                    struct nlattr **, unsigned long *);
    int         (*delete)(struct Qdisc *, unsigned long);
    void            (*walk)(struct Qdisc *, struct qdisc_walker * arg);

    /* Filter manipulation */
    struct tcf_proto ** (*tcf_chain)(struct Qdisc *, unsigned long);
    unsigned long       (*bind_tcf)(struct Qdisc *, unsigned long,
                    u32 classid);
    void            (*unbind_tcf)(struct Qdisc *, unsigned long);

    /* rtnetlink specific */
    int         (*dump)(struct Qdisc *, unsigned long,
                    struct sk_buff *skb, struct tcmsg*);
    int         (*dump_stats)(struct Qdisc *, unsigned long,
                    struct gnet_dump *);
};

struct Qdisc_ops {
    struct Qdisc_ops    *next;
    const struct Qdisc_class_ops    *cl_ops;
    char            id[IFNAMSIZ];
    int         priv_size;

    int             (*enqueue)(struct sk_buff *, struct Qdisc *);
    struct sk_buff *    (*dequeue)(struct Qdisc *);
    struct sk_buff *    (*peek)(struct Qdisc *);
    unsigned int        (*drop)(struct Qdisc *);

    int         (*init)(struct Qdisc *, struct nlattr *arg);
    void            (*reset)(struct Qdisc *);
    void            (*destroy)(struct Qdisc *);
    int         (*change)(struct Qdisc *, struct nlattr *arg);
    void            (*attach)(struct Qdisc *);

    int         (*dump)(struct Qdisc *, struct sk_buff *);
    int         (*dump_stats)(struct Qdisc *, struct gnet_dump *);

    struct module       *owner;
};


struct tcf_result {
    unsigned long   class;
    u32     classid;
};

struct tcf_proto_ops {
    struct tcf_proto_ops    *next;
    char            kind[IFNAMSIZ];

    int         (*classify)(struct sk_buff *,
                        const struct tcf_proto *,
                        struct tcf_result *);
    int         (*init)(struct tcf_proto*);
    void            (*destroy)(struct tcf_proto*);

    unsigned long       (*get)(struct tcf_proto*, u32 handle);
    void            (*put)(struct tcf_proto*, unsigned long);
    int         (*change)(struct sk_buff *,
                    struct tcf_proto*, unsigned long,
                    u32 handle, struct nlattr **,
                    unsigned long *);
    int         (*delete)(struct tcf_proto*, unsigned long);
    void            (*walk)(struct tcf_proto*, struct tcf_walker *arg);

    /* rtnetlink specific */
    int         (*dump)(struct tcf_proto*, unsigned long,
                    struct sk_buff *skb, struct tcmsg*);

    struct module       *owner;
};

struct tcf_proto {
    /* Fast access part */
    struct tcf_proto    *next;
    void            *root;
    int         (*classify)(struct sk_buff *,
                        const struct tcf_proto *,
                        struct tcf_result *);
    __be16          protocol;

    /* All the rest */
    u32         prio;
    u32         classid;
    struct Qdisc        *q;
    void            *data;
    const struct tcf_proto_ops  *ops;
};

struct qdisc_skb_cb {
    unsigned int        pkt_len;
    u16         slave_dev_queue_mapping;
    u16         _pad;
    unsigned char       data[20];
};

static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
{
    struct qdisc_skb_cb *qcb;

    BUILD_BUG_ON(sizeof(skb->cb) < offsetof(struct qdisc_skb_cb, data) + sz);
    BUILD_BUG_ON(sizeof(qcb->data) < sz);
}

static inline int qdisc_qlen(const struct Qdisc *q)
{
    return q->q.qlen;
}

static inline struct qdisc_skb_cb *qdisc_skb_cb(const struct sk_buff *skb)
{
    return (struct qdisc_skb_cb *)skb->cb;
}

static inline spinlock_t *qdisc_lock(struct Qdisc *qdisc)
{
    return &qdisc->q.lock;
}

static inline struct Qdisc *qdisc_root(const struct Qdisc *qdisc)
{
    return qdisc->dev_queue->qdisc;
}

static inline struct Qdisc *qdisc_root_sleeping(const struct Qdisc *qdisc)
{
    return qdisc->dev_queue->qdisc_sleeping;
}

/* The qdisc root lock is a mechanism by which to top level
 * of a qdisc tree can be locked from any qdisc node in the
 * forest.  This allows changing the configuration of some
 * aspect of the qdisc tree while blocking out asynchronous
 * qdisc access in the packet processing paths.
 *
 * It is only legal to do this when the root will not change
 * on us.  Otherwise we'll potentially lock the wrong qdisc
 * root.  This is enforced by holding the RTNL semaphore, which
 * all users of this lock accessor must do.
 */
static inline spinlock_t *qdisc_root_lock(const struct Qdisc *qdisc)
{
    struct Qdisc *root = qdisc_root(qdisc);

    ASSERT_RTNL();
    return qdisc_lock(root);
}

static inline spinlock_t *qdisc_root_sleeping_lock(const struct Qdisc *qdisc)
{
    struct Qdisc *root = qdisc_root_sleeping(qdisc);

    ASSERT_RTNL();
    return qdisc_lock(root);
}

static inline struct net_device *qdisc_dev(const struct Qdisc *qdisc)
{
    return qdisc->dev_queue->dev;
}

static inline void sch_tree_lock(const struct Qdisc *q)
{
    spin_lock_bh(qdisc_root_sleeping_lock(q));
}

static inline void sch_tree_unlock(const struct Qdisc *q)
{
    spin_unlock_bh(qdisc_root_sleeping_lock(q));
}

#define tcf_tree_lock(tp)   sch_tree_lock((tp)->q)
#define tcf_tree_unlock(tp) sch_tree_unlock((tp)->q)

extern struct Qdisc noop_qdisc;
extern struct Qdisc_ops noop_qdisc_ops;
extern struct Qdisc_ops pfifo_fast_ops;
extern struct Qdisc_ops mq_qdisc_ops;

struct Qdisc_class_common {
    u32         classid;
    struct hlist_node   hnode;
};

struct Qdisc_class_hash {
    struct hlist_head   *hash;
    unsigned int        hashsize;
    unsigned int        hashmask;
    unsigned int        hashelems;
};

static inline unsigned int qdisc_class_hash(u32 id, u32 mask)
{
    id ^= id >> 8;
    id ^= id >> 4;
    return id & mask;
}

static inline struct Qdisc_class_common *
qdisc_class_find(const struct Qdisc_class_hash *hash, u32 id)
{
    struct Qdisc_class_common *cl;
    struct hlist_node *n;
    unsigned int h;

    h = qdisc_class_hash(id, hash->hashmask);
    hlist_for_each_entry(cl, n, &hash->hash[h], hnode) {
        if (cl->classid == id)
            return cl;
    }
    return NULL;
}

extern int qdisc_class_hash_init(struct Qdisc_class_hash *);
extern void qdisc_class_hash_insert(struct Qdisc_class_hash *, struct Qdisc_class_common *);
extern void qdisc_class_hash_remove(struct Qdisc_class_hash *, struct Qdisc_class_common *);
extern void qdisc_class_hash_grow(struct Qdisc *, struct Qdisc_class_hash *);
extern void qdisc_class_hash_destroy(struct Qdisc_class_hash *);

extern void dev_init_scheduler(struct net_device *dev);
extern void dev_shutdown(struct net_device *dev);
extern void dev_activate(struct net_device *dev);
extern void dev_deactivate(struct net_device *dev);
extern void dev_deactivate_many(struct list_head *head);
extern struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
                     struct Qdisc *qdisc);
extern void qdisc_reset(struct Qdisc *qdisc);
extern void qdisc_destroy(struct Qdisc *qdisc);
extern void qdisc_tree_decrease_qlen(struct Qdisc *qdisc, unsigned int n);
extern struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
                 struct Qdisc_ops *ops);
extern struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
                       struct Qdisc_ops *ops, u32 parentid);
extern void __qdisc_calculate_pkt_len(struct sk_buff *skb,
                      const struct qdisc_size_table *stab);
extern void tcf_destroy(struct tcf_proto *tp);
extern void tcf_destroy_chain(struct tcf_proto **fl);

/* Reset all TX qdiscs greater then index of a device.  */
static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)
{
    struct Qdisc *qdisc;

    for (; i < dev->num_tx_queues; i++) {
        qdisc = netdev_get_tx_queue(dev, i)->qdisc;
        if (qdisc) {
            spin_lock_bh(qdisc_lock(qdisc));
            qdisc_reset(qdisc);
            spin_unlock_bh(qdisc_lock(qdisc));
        }
    }
}

static inline void qdisc_reset_all_tx(struct net_device *dev)
{
    qdisc_reset_all_tx_gt(dev, 0);
}

/* Are all TX queues of the device empty?  */
static inline bool qdisc_all_tx_empty(const struct net_device *dev)
{
    unsigned int i;
    for (i = 0; i < dev->num_tx_queues; i++) {
        struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
        const struct Qdisc *q = txq->qdisc;

        if (q->q.qlen)
            return false;
    }
    return true;
}

/* Are any of the TX qdiscs changing?  */
static inline bool qdisc_tx_changing(const struct net_device *dev)
{
    unsigned int i;
    for (i = 0; i < dev->num_tx_queues; i++) {
        struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
        if (txq->qdisc != txq->qdisc_sleeping)
            return true;
    }
    return false;
}

/* Is the device using the noop qdisc on all queues?  */
static inline bool qdisc_tx_is_noop(const struct net_device *dev)
{
    unsigned int i;
    for (i = 0; i < dev->num_tx_queues; i++) {
        struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
        if (txq->qdisc != &noop_qdisc)
            return false;
    }
    return true;
}

static inline unsigned int qdisc_pkt_len(const struct sk_buff *skb)
{
    return qdisc_skb_cb(skb)->pkt_len;
}

/* additional qdisc xmit flags (NET_XMIT_MASK in linux/netdevice.h) */
enum net_xmit_qdisc_t {
    __NET_XMIT_STOLEN = 0x00010000,
    __NET_XMIT_BYPASS = 0x00020000,
};

#ifdef CONFIG_NET_CLS_ACT
#define net_xmit_drop_count(e)  ((e) & __NET_XMIT_STOLEN ? 0 : 1)
#else
#define net_xmit_drop_count(e)  (1)
#endif

static inline void qdisc_calculate_pkt_len(struct sk_buff *skb,
                       const struct Qdisc *sch)
{
#ifdef CONFIG_NET_SCHED
    struct qdisc_size_table *stab = rcu_dereference_bh(sch->stab);

    if (stab)
        __qdisc_calculate_pkt_len(skb, stab);
#endif
}

static inline int qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
    qdisc_calculate_pkt_len(skb, sch);
    return sch->enqueue(skb, sch);
}

static inline int qdisc_enqueue_root(struct sk_buff *skb, struct Qdisc *sch)
{
    qdisc_skb_cb(skb)->pkt_len = skb->len;
    return qdisc_enqueue(skb, sch) & NET_XMIT_MASK;
}


static inline void bstats_update(struct gnet_stats_basic_packed *bstats,
                 const struct sk_buff *skb)
{
    bstats->bytes += qdisc_pkt_len(skb);
    bstats->packets += skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1;
}

static inline void qdisc_bstats_update(struct Qdisc *sch,
                       const struct sk_buff *skb)
{
    bstats_update(&sch->bstats, skb);
}

static inline int __qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch,
                       struct sk_buff_head *list)
{
    __skb_queue_tail(list, skb);
    sch->qstats.backlog += qdisc_pkt_len(skb);

    return NET_XMIT_SUCCESS;
}

static inline int qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch)
{
    return __qdisc_enqueue_tail(skb, sch, &sch->q);
}

static inline struct sk_buff *__qdisc_dequeue_head(struct Qdisc *sch,
                           struct sk_buff_head *list)
{
    struct sk_buff *skb = __skb_dequeue(list);

    if (likely(skb != NULL)) {
        sch->qstats.backlog -= qdisc_pkt_len(skb);
        qdisc_bstats_update(sch, skb);
    }

    return skb;
}

static inline struct sk_buff *qdisc_dequeue_head(struct Qdisc *sch)
{
    return __qdisc_dequeue_head(sch, &sch->q);
}

static inline unsigned int __qdisc_queue_drop_head(struct Qdisc *sch,
                          struct sk_buff_head *list)
{
    struct sk_buff *skb = __skb_dequeue(list);

    if (likely(skb != NULL)) {
        unsigned int len = qdisc_pkt_len(skb);
        sch->qstats.backlog -= len;
        kfree_skb(skb);
        return len;
    }

    return 0;
}

static inline unsigned int qdisc_queue_drop_head(struct Qdisc *sch)
{
    return __qdisc_queue_drop_head(sch, &sch->q);
}

static inline struct sk_buff *__qdisc_dequeue_tail(struct Qdisc *sch,
                           struct sk_buff_head *list)
{
    struct sk_buff *skb = __skb_dequeue_tail(list);

    if (likely(skb != NULL))
        sch->qstats.backlog -= qdisc_pkt_len(skb);

    return skb;
}

static inline struct sk_buff *qdisc_dequeue_tail(struct Qdisc *sch)
{
    return __qdisc_dequeue_tail(sch, &sch->q);
}

static inline struct sk_buff *qdisc_peek_head(struct Qdisc *sch)
{
    return skb_peek(&sch->q);
}

/* generic pseudo peek method for non-work-conserving qdisc */
static inline struct sk_buff *qdisc_peek_dequeued(struct Qdisc *sch)
{
    /* we can reuse ->gso_skb because peek isn't called for root qdiscs */
    if (!sch->gso_skb) {
        sch->gso_skb = sch->dequeue(sch);
        if (sch->gso_skb)
            /* it's still part of the queue */
            sch->q.qlen++;
    }

    return sch->gso_skb;
}

/* use instead of qdisc->dequeue() for all qdiscs queried with ->peek() */
static inline struct sk_buff *qdisc_dequeue_peeked(struct Qdisc *sch)
{
    struct sk_buff *skb = sch->gso_skb;

    if (skb) {
        sch->gso_skb = NULL;
        sch->q.qlen--;
    } else {
        skb = sch->dequeue(sch);
    }

    return skb;
}

static inline void __qdisc_reset_queue(struct Qdisc *sch,
                       struct sk_buff_head *list)
{
    /*
     * We do not know the backlog in bytes of this list, it
     * is up to the caller to correct it
     */
    __skb_queue_purge(list);
}

static inline void qdisc_reset_queue(struct Qdisc *sch)
{
    __qdisc_reset_queue(sch, &sch->q);
    sch->qstats.backlog = 0;
}

static inline unsigned int __qdisc_queue_drop(struct Qdisc *sch,
                          struct sk_buff_head *list)
{
    struct sk_buff *skb = __qdisc_dequeue_tail(sch, list);

    if (likely(skb != NULL)) {
        unsigned int len = qdisc_pkt_len(skb);
        kfree_skb(skb);
        return len;
    }

    return 0;
}

static inline unsigned int qdisc_queue_drop(struct Qdisc *sch)
{
    return __qdisc_queue_drop(sch, &sch->q);
}

static inline int qdisc_drop(struct sk_buff *skb, struct Qdisc *sch)
{
    kfree_skb(skb);
    sch->qstats.drops++;

    return NET_XMIT_DROP;
}

static inline int qdisc_reshape_fail(struct sk_buff *skb, struct Qdisc *sch)
{
    sch->qstats.drops++;

#ifdef CONFIG_NET_CLS_ACT
    if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
        goto drop;

    return NET_XMIT_SUCCESS;

drop:
#endif
    kfree_skb(skb);
    return NET_XMIT_DROP;
}

/* Length to Time (L2T) lookup in a qdisc_rate_table, to determine how
   long it will take to send a packet given its size.
 */
static inline u32 qdisc_l2t(struct qdisc_rate_table* rtab, unsigned int pktlen)
{
    int slot = pktlen + rtab->rate.cell_align + rtab->rate.overhead;
    if (slot < 0)
        slot = 0;
    slot >>= rtab->rate.cell_log;
    if (slot > 255)
        return rtab->data[255]*(slot >> 8) + rtab->data[slot & 0xFF];
    return rtab->data[slot];
}

#ifdef CONFIG_NET_CLS_ACT
static inline struct sk_buff *skb_act_clone(struct sk_buff *skb, gfp_t gfp_mask,
                        int action)
{
    struct sk_buff *n;

    n = skb_clone(skb, gfp_mask);

    if (n) {
        n->tc_verd = SET_TC_VERD(n->tc_verd, 0);
        n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
        n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
    }
    return n;
}
#endif

#endif