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linux/include/net/sch_generic.h
Eric Dumazet ef352e7cdf net_sched: fix THROTTLED/RUNNING race 
commit fd245a4adb (net_sched: move TCQ_F_THROTTLED flag)
added a race.

qdisc_watchdog() is run from softirq, so special care should be taken or
we can lose one state transition (THROTTLED/RUNNING)

Prior to fd245a4adb, we were manipulating q->flags (qdisc->flags &=
~TCQ_F_THROTTLED;) and this manipulation could only race with
qdisc_warn_nonwc().

Since we want to avoid atomic ops in qdisc fast path - it was the
meaning of commit 3711210576 (QDISC_STATE_RUNNING dont need atomic
bit ops) - fix is to move THROTTLE bit into 'state' field, this one
being manipulated with SMP and IRQ safe operations.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-03-24 00:13:14 -07:00

664 lines
16 KiB
C
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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/module.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 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;
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*, 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 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*, struct tcf_proto*,
struct tcf_result *);
__be16 protocol;
/* All the rest */
u32 prio;
u32 classid;
struct Qdisc *q;
void *data;
struct tcf_proto_ops *ops;
};
struct qdisc_skb_cb {
unsigned int pkt_len;
long data[];
};
static inline int qdisc_qlen(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(struct Qdisc *qdisc)
{
return qdisc->dev_queue->qdisc;
}
static inline struct Qdisc *qdisc_root_sleeping(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(struct Qdisc *qdisc)
{
struct Qdisc *root = qdisc_root(qdisc);
ASSERT_RTNL();
return qdisc_lock(root);
}
static inline spinlock_t *qdisc_root_sleeping_lock(struct Qdisc *qdisc)
{
struct Qdisc *root = qdisc_root_sleeping(qdisc);
ASSERT_RTNL();
return qdisc_lock(root);
}
static inline struct net_device *qdisc_dev(struct Qdisc *qdisc)
{
return qdisc->dev_queue->dev;
}
static inline void sch_tree_lock(struct Qdisc *q)
{
spin_lock_bh(qdisc_root_sleeping_lock(q));
}
static inline void sch_tree_unlock(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(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(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
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