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net: qdisc: use rcu prefix and silence sparse warnings 

Add __rcu notation to qdisc handling by doing this we can make
smatch output more legible. And anyways some of the cases should
be using rcu_dereference() see qdisc_all_tx_empty(),
qdisc_tx_chainging(), and so on.

Also *wake_queue() API is commonly called from driver timer routines
without rcu lock or rtnl lock. So I added rcu_read_lock() blocks
around netif_wake_subqueue and netif_tx_wake_queue.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
John Fastabend 2014-09-12 20:04:52 -07:00 committed by David S. Miller
parent d1015645dd
commit 46e5da40ae
6 changed files with 82 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
include/linux/netdevice.h
View File

@ -543,7 +543,7 @@ struct netdev_queue {
* read mostly part
*/
struct net_device *dev;
struct Qdisc *qdisc;
struct Qdisc __rcu *qdisc;
struct Qdisc *qdisc_sleeping;
#ifdef CONFIG_SYSFS
struct kobject kobj;
@ -2356,12 +2356,7 @@ static inline void input_queue_tail_incr_save(struct softnet_data *sd,
DECLARE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
void __netif_schedule(struct Qdisc *q);
static inline void netif_schedule_queue(struct netdev_queue *txq)
{
if (!(txq->state & QUEUE_STATE_ANY_XOFF))
__netif_schedule(txq->qdisc);
}
void netif_schedule_queue(struct netdev_queue *txq);
static inline void netif_tx_schedule_all(struct net_device *dev)
{
@ -2397,11 +2392,7 @@ static inline void netif_tx_start_all_queues(struct net_device *dev)
}
}
static inline void netif_tx_wake_queue(struct netdev_queue *dev_queue)
{
if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state))
__netif_schedule(dev_queue->qdisc);
}
void netif_tx_wake_queue(struct netdev_queue *dev_queue);
/**
* netif_wake_queue - restart transmit
@ -2673,19 +2664,7 @@ static inline bool netif_subqueue_stopped(const struct net_device *dev,
return __netif_subqueue_stopped(dev, skb_get_queue_mapping(skb));
}
/**
* netif_wake_subqueue - allow sending packets on subqueue
* @dev: network device
* @queue_index: sub queue index
*
* Resume individual transmit queue of a device with multiple transmit queues.
*/
static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
{
struct netdev_queue *txq = netdev_get_tx_queue(dev, queue_index);
if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state))
__netif_schedule(txq->qdisc);
}
void netif_wake_subqueue(struct net_device *dev, u16 queue_index);
#ifdef CONFIG_XPS
int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,

21
include/net/sch_generic.h
View File

@ -259,7 +259,9 @@ static inline spinlock_t *qdisc_lock(struct Qdisc *qdisc)
static inline struct Qdisc *qdisc_root(const struct Qdisc *qdisc)
{
return qdisc->dev_queue->qdisc;
struct Qdisc *q = rcu_dereference_rtnl(qdisc->dev_queue->qdisc);
return q;
}
static inline struct Qdisc *qdisc_root_sleeping(const struct Qdisc *qdisc)
@ -384,7 +386,7 @@ 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;
qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc);
if (qdisc) {
spin_lock_bh(qdisc_lock(qdisc));
qdisc_reset(qdisc);
@ -402,13 +404,18 @@ static inline void qdisc_reset_all_tx(struct net_device *dev)
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 = txq->qdisc;
const struct Qdisc *q = rcu_dereference(txq->qdisc);
if (q->q.qlen)
if (q->q.qlen) {
rcu_read_unlock();
return false;
}
}
rcu_read_unlock();
return true;
}
@ -416,9 +423,10 @@ static inline bool qdisc_all_tx_empty(const struct net_device *dev)
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)
if (rcu_access_pointer(txq->qdisc) != txq->qdisc_sleeping)
return true;
}
return false;
@ -428,9 +436,10 @@ static inline bool qdisc_tx_changing(const struct net_device *dev)
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)
if (rcu_access_pointer(txq->qdisc) != &noop_qdisc)
return false;
}
return true;

51
net/core/dev.c
View File

@ -2177,6 +2177,53 @@ static struct dev_kfree_skb_cb *get_kfree_skb_cb(const struct sk_buff *skb)
return (struct dev_kfree_skb_cb *)skb->cb;
}
void netif_schedule_queue(struct netdev_queue *txq)
{
rcu_read_lock();
if (!(txq->state & QUEUE_STATE_ANY_XOFF)) {
struct Qdisc *q = rcu_dereference(txq->qdisc);
__netif_schedule(q);
}
rcu_read_unlock();
}
EXPORT_SYMBOL(netif_schedule_queue);
/**
* netif_wake_subqueue - allow sending packets on subqueue
* @dev: network device
* @queue_index: sub queue index
*
* Resume individual transmit queue of a device with multiple transmit queues.
*/
void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
{
struct netdev_queue *txq = netdev_get_tx_queue(dev, queue_index);
if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state)) {
struct Qdisc *q;
rcu_read_lock();
q = rcu_dereference(txq->qdisc);
__netif_schedule(q);
rcu_read_unlock();
}
}
EXPORT_SYMBOL(netif_wake_subqueue);
void netif_tx_wake_queue(struct netdev_queue *dev_queue)
{
if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state)) {
struct Qdisc *q;
rcu_read_lock();
q = rcu_dereference(dev_queue->qdisc);
__netif_schedule(q);
rcu_read_unlock();
}
}
EXPORT_SYMBOL(netif_tx_wake_queue);
void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
{
unsigned long flags;
@ -3432,7 +3479,7 @@ static int ing_filter(struct sk_buff *skb, struct netdev_queue *rxq)
skb->tc_verd = SET_TC_RTTL(skb->tc_verd, ttl);
skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_INGRESS);
q = rxq->qdisc;
q = rcu_dereference(rxq->qdisc);
if (q != &noop_qdisc) {
spin_lock(qdisc_lock(q));
if (likely(!test_bit(__QDISC_STATE_DEACTIVATED, &q->state)))
@ -3449,7 +3496,7 @@ static inline struct sk_buff *handle_ing(struct sk_buff *skb,
{
struct netdev_queue *rxq = rcu_dereference(skb->dev->ingress_queue);
if (!rxq || rxq->qdisc == &noop_qdisc)
if (!rxq || rcu_access_pointer(rxq->qdisc) == &noop_qdisc)
goto out;
if (*pt_prev) {

4
net/sched/sch_generic.c
View File

@ -783,7 +783,7 @@ static void dev_deactivate_queue(struct net_device *dev,
struct Qdisc *qdisc_default = _qdisc_default;
struct Qdisc *qdisc;
qdisc = dev_queue->qdisc;
qdisc = rtnl_dereference(dev_queue->qdisc);
if (qdisc) {
spin_lock_bh(qdisc_lock(qdisc));
@ -876,7 +876,7 @@ static void dev_init_scheduler_queue(struct net_device *dev,
{
struct Qdisc *qdisc = _qdisc;
dev_queue->qdisc = qdisc;
rcu_assign_pointer(dev_queue->qdisc, qdisc);
dev_queue->qdisc_sleeping = qdisc;
}

6
net/sched/sch_mqprio.c
View File

@ -231,7 +231,7 @@ static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
memset(&sch->qstats, 0, sizeof(sch->qstats));
for (i = 0; i < dev->num_tx_queues; i++) {
qdisc = netdev_get_tx_queue(dev, i)->qdisc;
qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc);
spin_lock_bh(qdisc_lock(qdisc));
sch->q.qlen += qdisc->q.qlen;
sch->bstats.bytes += qdisc->bstats.bytes;
@ -340,7 +340,9 @@ static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
spin_unlock_bh(d->lock);
for (i = tc.offset; i < tc.offset + tc.count; i++) {
qdisc = netdev_get_tx_queue(dev, i)->qdisc;
struct netdev_queue *q = netdev_get_tx_queue(dev, i);
qdisc = rtnl_dereference(q->qdisc);
spin_lock_bh(qdisc_lock(qdisc));
bstats.bytes += qdisc->bstats.bytes;
bstats.packets += qdisc->bstats.packets;

13
net/sched/sch_teql.c
View File

@ -96,11 +96,14 @@ teql_dequeue(struct Qdisc *sch)
struct teql_sched_data *dat = qdisc_priv(sch);
struct netdev_queue *dat_queue;
struct sk_buff *skb;
struct Qdisc *q;
skb = __skb_dequeue(&dat->q);
dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
q = rcu_dereference_bh(dat_queue->qdisc);
if (skb == NULL) {
struct net_device *m = qdisc_dev(dat_queue->qdisc);
struct net_device *m = qdisc_dev(q);
if (m) {
dat->m->slaves = sch;
netif_wake_queue(m);
@ -108,7 +111,7 @@ teql_dequeue(struct Qdisc *sch)
} else {
qdisc_bstats_update(sch, skb);
}
sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
sch->q.qlen = dat->q.qlen + q->q.qlen;
return skb;
}
@ -157,9 +160,9 @@ teql_destroy(struct Qdisc *sch)
txq = netdev_get_tx_queue(master->dev, 0);
master->slaves = NULL;
root_lock = qdisc_root_sleeping_lock(txq->qdisc);
root_lock = qdisc_root_sleeping_lock(rtnl_dereference(txq->qdisc));
spin_lock_bh(root_lock);
qdisc_reset(txq->qdisc);
qdisc_reset(rtnl_dereference(txq->qdisc));
spin_unlock_bh(root_lock);
}
}
@ -266,7 +269,7 @@ static inline int teql_resolve(struct sk_buff *skb,
struct dst_entry *dst = skb_dst(skb);
int res;
if (txq->qdisc == &noop_qdisc)
if (rcu_access_pointer(txq->qdisc) == &noop_qdisc)
return -ENODEV;
if (!dev->header_ops || !dst)