Merge tag 'drm-misc-fixes-2018-01-24' of git://anongit.freedesktop.org/drm/drm-misc...

[mirror_ubuntu-bionic-kernel.git] / include / net / sch_generic.h

/* SPDX-License-Identifier: GPL-2.0 */
#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 <linux/percpu.h>
#include <linux/dynamic_queue_limits.h>
#include <linux/list.h>
#include <linux/refcount.h>
#include <linux/workqueue.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,
};

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

/* similar to sk_buff_head, but skb->prev pointer is undefined. */
struct qdisc_skb_head {
        struct sk_buff  *head;
        struct sk_buff  *tail;
        __u32           qlen;
        spinlock_t      lock;
};

struct Qdisc {
        int                     (*enqueue)(struct sk_buff *skb,
                                           struct Qdisc *sch,
                                           struct sk_buff **to_free);
        struct sk_buff *        (*dequeue)(struct Qdisc *sch);
        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_ONETXQUEUE        0x10 /* dequeue_skb() can assume all skbs are for
                                      * q->dev_queue : It can test
                                      * netif_xmit_frozen_or_stopped() before
                                      * dequeueing next packet.
                                      * Its true for MQ/MQPRIO slaves, or non
                                      * multiqueue device.
                                      */
#define TCQ_F_WARN_NONWC        (1 << 16)
#define TCQ_F_CPUSTATS          0x20 /* run using percpu statistics */
#define TCQ_F_NOPARENT          0x40 /* root of its hierarchy :
                                      * qdisc_tree_decrease_qlen() should stop.
                                      */
#define TCQ_F_INVISIBLE         0x80 /* invisible by default in dump */
#define TCQ_F_OFFLOADED         0x200 /* qdisc is offloaded to HW */
        u32                     limit;
        const struct Qdisc_ops  *ops;
        struct qdisc_size_table __rcu *stab;
        struct hlist_node       hash;
        u32                     handle;
        u32                     parent;

        struct netdev_queue     *dev_queue;

        struct net_rate_estimator __rcu *rate_est;
        struct gnet_stats_basic_cpu __percpu *cpu_bstats;
        struct gnet_stats_queue __percpu *cpu_qstats;

        /*
         * For performance sake on SMP, we put highly modified fields at the end
         */
        struct sk_buff          *gso_skb ____cacheline_aligned_in_smp;
        struct qdisc_skb_head   q;
        struct gnet_stats_basic_packed bstats;
        seqcount_t              running;
        struct gnet_stats_queue qstats;
        unsigned long           state;
        struct Qdisc            *next_sched;
        struct sk_buff          *skb_bad_txq;
        int                     padded;
        refcount_t              refcnt;

        spinlock_t              busylock ____cacheline_aligned_in_smp;
};

static inline void qdisc_refcount_inc(struct Qdisc *qdisc)
{
        if (qdisc->flags & TCQ_F_BUILTIN)
                return;
        refcount_inc(&qdisc->refcnt);
}

static inline bool qdisc_is_running(const struct Qdisc *qdisc)
{
        return (raw_read_seqcount(&qdisc->running) & 1) ? true : false;
}

static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
        if (qdisc_is_running(qdisc))
                return false;
        /* Variant of write_seqcount_begin() telling lockdep a trylock
         * was attempted.
         */
        raw_write_seqcount_begin(&qdisc->running);
        seqcount_acquire(&qdisc->running.dep_map, 0, 1, _RET_IP_);
        return true;
}

static inline void qdisc_run_end(struct Qdisc *qdisc)
{
        write_seqcount_end(&qdisc->running);
}

static inline bool qdisc_may_bulk(const struct Qdisc *qdisc)
{
        return qdisc->flags & TCQ_F_ONETXQUEUE;
}

static inline int qdisc_avail_bulklimit(const struct netdev_queue *txq)
{
#ifdef CONFIG_BQL
        /* Non-BQL migrated drivers will return 0, too. */
        return dql_avail(&txq->dql);
#else
        return 0;
#endif
}

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           (*find)(struct Qdisc *, u32 classid);
        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_block *      (*tcf_block)(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;
        unsigned int            static_flags;

        int                     (*enqueue)(struct sk_buff *skb,
                                           struct Qdisc *sch,
                                           struct sk_buff **to_free);
        struct sk_buff *        (*dequeue)(struct Qdisc *);
        struct sk_buff *        (*peek)(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 {
        union {
                struct {
                        unsigned long   class;
                        u32             classid;
                };
                const struct tcf_proto *goto_tp;
        };
};

struct tcf_proto_ops {
        struct list_head        head;
        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*);

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

        /* rtnetlink specific */
        int                     (*dump)(struct net*, struct tcf_proto*, void *,
                                        struct sk_buff *skb, struct tcmsg*);

        struct module           *owner;
};

struct tcf_proto {
        /* Fast access part */
        struct tcf_proto __rcu  *next;
        void __rcu              *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 tcf_chain        *chain;
        struct rcu_head         rcu;
};

struct qdisc_skb_cb {
        unsigned int            pkt_len;
        u16                     slave_dev_queue_mapping;
        u16                     tc_classid;
#define QDISC_CB_PRIV_LEN 20
        unsigned char           data[QDISC_CB_PRIV_LEN];
};

typedef void tcf_chain_head_change_t(struct tcf_proto *tp_head, void *priv);

struct tcf_chain {
        struct tcf_proto __rcu *filter_chain;
        tcf_chain_head_change_t *chain_head_change;
        void *chain_head_change_priv;
        struct list_head list;
        struct tcf_block *block;
        u32 index; /* chain index */
        unsigned int refcnt;
};

struct tcf_block {
        struct list_head chain_list;
        struct net *net;
        struct Qdisc *q;
        struct list_head cb_list;
        struct work_struct work;
};

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)
{
        struct Qdisc *q = rcu_dereference_rtnl(qdisc->dev_queue->qdisc);

        return q;
}

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 seqcount_t *qdisc_root_sleeping_running(const struct Qdisc *qdisc)
{
        struct Qdisc *root = qdisc_root_sleeping(qdisc);

        ASSERT_RTNL();
        return &root->running;
}

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));
}

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;
extern struct Qdisc_ops noqueue_qdisc_ops;
extern const struct Qdisc_ops *default_qdisc_ops;
static inline const struct Qdisc_ops *
get_default_qdisc_ops(const struct net_device *dev, int ntx)
{
        return ntx < dev->real_num_tx_queues ?
                        default_qdisc_ops : &pfifo_fast_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;
        unsigned int h;

        if (!id)
                return NULL;

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

static inline int tc_classid_to_hwtc(struct net_device *dev, u32 classid)
{
        u32 hwtc = TC_H_MIN(classid) - TC_H_MIN_PRIORITY;

        return (hwtc < netdev_get_num_tc(dev)) ? hwtc : -EINVAL;
}

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

void dev_init_scheduler(struct net_device *dev);
void dev_shutdown(struct net_device *dev);
void dev_activate(struct net_device *dev);
void dev_deactivate(struct net_device *dev);
void dev_deactivate_many(struct list_head *head);
struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
                              struct Qdisc *qdisc);
void qdisc_reset(struct Qdisc *qdisc);
void qdisc_destroy(struct Qdisc *qdisc);
void qdisc_tree_reduce_backlog(struct Qdisc *qdisc, unsigned int n,
                               unsigned int len);
struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
                          const struct Qdisc_ops *ops);
void qdisc_free(struct Qdisc *qdisc);
struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
                                const struct Qdisc_ops *ops, u32 parentid);
void __qdisc_calculate_pkt_len(struct sk_buff *skb,
                               const struct qdisc_size_table *stab);
int skb_do_redirect(struct sk_buff *);

static inline void skb_reset_tc(struct sk_buff *skb)
{
#ifdef CONFIG_NET_CLS_ACT
        skb->tc_redirected = 0;
#endif
}

static inline bool skb_at_tc_ingress(const struct sk_buff *skb)
{
#ifdef CONFIG_NET_CLS_ACT
        return skb->tc_at_ingress;
#else
        return false;
#endif
}

static inline bool skb_skip_tc_classify(struct sk_buff *skb)
{
#ifdef CONFIG_NET_CLS_ACT
        if (skb->tc_skip_classify) {
                skb->tc_skip_classify = 0;
                return true;
        }
#endif
        return false;
}

/* 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 = rtnl_dereference(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;

        rcu_read_lock();
        for (i = 0; i < dev->num_tx_queues; i++) {
                struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
                const struct Qdisc *q = rcu_dereference(txq->qdisc);

                if (q->q.qlen) {
                        rcu_read_unlock();
                        return false;
                }
        }
        rcu_read_unlock();
        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 (rcu_access_pointer(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 (rcu_access_pointer(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,
                                struct sk_buff **to_free)
{
        qdisc_calculate_pkt_len(skb, sch);
        return sch->enqueue(skb, sch, to_free);
}

static inline bool qdisc_is_percpu_stats(const struct Qdisc *q)
{
        return q->flags & TCQ_F_CPUSTATS;
}

static inline void _bstats_update(struct gnet_stats_basic_packed *bstats,
                                  __u64 bytes, __u32 packets)
{
        bstats->bytes += bytes;
        bstats->packets += packets;
}

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

static inline void _bstats_cpu_update(struct gnet_stats_basic_cpu *bstats,
                                      __u64 bytes, __u32 packets)
{
        u64_stats_update_begin(&bstats->syncp);
        _bstats_update(&bstats->bstats, bytes, packets);
        u64_stats_update_end(&bstats->syncp);
}

static inline void bstats_cpu_update(struct gnet_stats_basic_cpu *bstats,
                                     const struct sk_buff *skb)
{
        u64_stats_update_begin(&bstats->syncp);
        bstats_update(&bstats->bstats, skb);
        u64_stats_update_end(&bstats->syncp);
}

static inline void qdisc_bstats_cpu_update(struct Qdisc *sch,
                                           const struct sk_buff *skb)
{
        bstats_cpu_update(this_cpu_ptr(sch->cpu_bstats), skb);
}

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

static inline void qdisc_qstats_backlog_dec(struct Qdisc *sch,
                                            const struct sk_buff *skb)
{
        sch->qstats.backlog -= qdisc_pkt_len(skb);
}

static inline void qdisc_qstats_backlog_inc(struct Qdisc *sch,
                                            const struct sk_buff *skb)
{
        sch->qstats.backlog += qdisc_pkt_len(skb);
}

static inline void __qdisc_qstats_drop(struct Qdisc *sch, int count)
{
        sch->qstats.drops += count;
}

static inline void qstats_drop_inc(struct gnet_stats_queue *qstats)
{
        qstats->drops++;
}

static inline void qstats_overlimit_inc(struct gnet_stats_queue *qstats)
{
        qstats->overlimits++;
}

static inline void qdisc_qstats_drop(struct Qdisc *sch)
{
        qstats_drop_inc(&sch->qstats);
}

static inline void qdisc_qstats_cpu_drop(struct Qdisc *sch)
{
        this_cpu_inc(sch->cpu_qstats->drops);
}

static inline void qdisc_qstats_overlimit(struct Qdisc *sch)
{
        sch->qstats.overlimits++;
}

static inline void qdisc_skb_head_init(struct qdisc_skb_head *qh)
{
        qh->head = NULL;
        qh->tail = NULL;
        qh->qlen = 0;
}

static inline int __qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch,
                                       struct qdisc_skb_head *qh)
{
        struct sk_buff *last = qh->tail;

        if (last) {
                skb->next = NULL;
                last->next = skb;
                qh->tail = skb;
        } else {
                qh->tail = skb;
                qh->head = skb;
        }
        qh->qlen++;
        qdisc_qstats_backlog_inc(sch, 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_skb_head *qh)
{
        struct sk_buff *skb = qh->head;

        if (likely(skb != NULL)) {
                qh->head = skb->next;
                qh->qlen--;
                if (qh->head == NULL)
                        qh->tail = NULL;
                skb->next = NULL;
        }

        return skb;
}

static inline struct sk_buff *qdisc_dequeue_head(struct Qdisc *sch)
{
        struct sk_buff *skb = __qdisc_dequeue_head(&sch->q);

        if (likely(skb != NULL)) {
                qdisc_qstats_backlog_dec(sch, skb);
                qdisc_bstats_update(sch, skb);
        }

        return skb;
}

/* Instead of calling kfree_skb() while root qdisc lock is held,
 * queue the skb for future freeing at end of __dev_xmit_skb()
 */
static inline void __qdisc_drop(struct sk_buff *skb, struct sk_buff **to_free)
{
        skb->next = *to_free;
        *to_free = skb;
}

static inline unsigned int __qdisc_queue_drop_head(struct Qdisc *sch,
                                                   struct qdisc_skb_head *qh,
                                                   struct sk_buff **to_free)
{
        struct sk_buff *skb = __qdisc_dequeue_head(qh);

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

                qdisc_qstats_backlog_dec(sch, skb);
                __qdisc_drop(skb, to_free);
                return len;
        }

        return 0;
}

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

static inline struct sk_buff *qdisc_peek_head(struct Qdisc *sch)
{
        const struct qdisc_skb_head *qh = &sch->q;

        return qh->head;
}

/* 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 */
                        qdisc_qstats_backlog_inc(sch, sch->gso_skb);
                        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;
                qdisc_qstats_backlog_dec(sch, skb);
                sch->q.qlen--;
        } else {
                skb = sch->dequeue(sch);
        }

        return skb;
}

static inline void __qdisc_reset_queue(struct qdisc_skb_head *qh)
{
        /*
         * We do not know the backlog in bytes of this list, it
         * is up to the caller to correct it
         */
        ASSERT_RTNL();
        if (qh->qlen) {
                rtnl_kfree_skbs(qh->head, qh->tail);

                qh->head = NULL;
                qh->tail = NULL;
                qh->qlen = 0;
        }
}

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

static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new,
                                          struct Qdisc **pold)
{
        struct Qdisc *old;

        sch_tree_lock(sch);
        old = *pold;
        *pold = new;
        if (old != NULL) {
                unsigned int qlen = old->q.qlen;
                unsigned int backlog = old->qstats.backlog;

                qdisc_reset(old);
                qdisc_tree_reduce_backlog(old, qlen, backlog);
        }
        sch_tree_unlock(sch);

        return old;
}

static inline void rtnl_qdisc_drop(struct sk_buff *skb, struct Qdisc *sch)
{
        rtnl_kfree_skbs(skb, skb);
        qdisc_qstats_drop(sch);
}


static inline int qdisc_drop(struct sk_buff *skb, struct Qdisc *sch,
                             struct sk_buff **to_free)
{
        __qdisc_drop(skb, to_free);
        qdisc_qstats_drop(sch);

        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];
}

struct psched_ratecfg {
        u64     rate_bytes_ps; /* bytes per second */
        u32     mult;
        u16     overhead;
        u8      linklayer;
        u8      shift;
};

static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
                                unsigned int len)
{
        len += r->overhead;

        if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
                return ((u64)(DIV_ROUND_UP(len,48)*53) * r->mult) >> r->shift;

        return ((u64)len * r->mult) >> r->shift;
}

void psched_ratecfg_precompute(struct psched_ratecfg *r,
                               const struct tc_ratespec *conf,
                               u64 rate64);

static inline void psched_ratecfg_getrate(struct tc_ratespec *res,
                                          const struct psched_ratecfg *r)
{
        memset(res, 0, sizeof(*res));

        /* legacy struct tc_ratespec has a 32bit @rate field
         * Qdisc using 64bit rate should add new attributes
         * in order to maintain compatibility.
         */
        res->rate = min_t(u64, r->rate_bytes_ps, ~0U);

        res->overhead = r->overhead;
        res->linklayer = (r->linklayer & TC_LINKLAYER_MASK);
}

/* Mini Qdisc serves for specific needs of ingress/clsact Qdisc.
 * The fast path only needs to access filter list and to update stats
 */
struct mini_Qdisc {
        struct tcf_proto *filter_list;
        struct gnet_stats_basic_cpu __percpu *cpu_bstats;
        struct gnet_stats_queue __percpu *cpu_qstats;
        struct rcu_head rcu;
};

static inline void mini_qdisc_bstats_cpu_update(struct mini_Qdisc *miniq,
                                                const struct sk_buff *skb)
{
        bstats_cpu_update(this_cpu_ptr(miniq->cpu_bstats), skb);
}

static inline void mini_qdisc_qstats_cpu_drop(struct mini_Qdisc *miniq)
{
        this_cpu_inc(miniq->cpu_qstats->drops);
}

struct mini_Qdisc_pair {
        struct mini_Qdisc miniq1;
        struct mini_Qdisc miniq2;
        struct mini_Qdisc __rcu **p_miniq;
};

void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
                          struct tcf_proto *tp_head);
void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
                          struct mini_Qdisc __rcu **p_miniq);

#endif