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net: remove dst gc related code
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This patch removes all dst gc related code and all the dst free
functions

Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Wei Wang authored and David S. Miller committed Jun 18, 2017
1 parent 560fd93 commit 5b7c9a8
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Showing 3 changed files with 0 additions and 235 deletions.
21 changes: 0 additions & 21 deletions include/net/dst.h
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Original file line number Diff line number Diff line change
Expand Up @@ -425,28 +425,9 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
void dst_init(struct dst_entry *dst, struct dst_ops *ops,
struct net_device *dev, int initial_ref, int initial_obsolete,
unsigned short flags);
void __dst_free(struct dst_entry *dst);
struct dst_entry *dst_destroy(struct dst_entry *dst);
void dst_dev_put(struct dst_entry *dst);

static inline void dst_free(struct dst_entry *dst)
{
if (dst->obsolete > 0)
return;
if (!atomic_read(&dst->__refcnt)) {
dst = dst_destroy(dst);
if (!dst)
return;
}
__dst_free(dst);
}

static inline void dst_rcu_free(struct rcu_head *head)
{
struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
dst_free(dst);
}

static inline void dst_confirm(struct dst_entry *dst)
{
}
Expand Down Expand Up @@ -508,8 +489,6 @@ static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
return dst;
}

void dst_subsys_init(void);

/* Flags for xfrm_lookup flags argument. */
enum {
XFRM_LOOKUP_ICMP = 1 << 0,
Expand Down
1 change: 0 additions & 1 deletion net/core/dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8681,7 +8681,6 @@ static int __init net_dev_init(void)
rc = cpuhp_setup_state_nocalls(CPUHP_NET_DEV_DEAD, "net/dev:dead",
NULL, dev_cpu_dead);
WARN_ON(rc < 0);
dst_subsys_init();
rc = 0;
out:
return rc;
Expand Down
213 changes: 0 additions & 213 deletions net/core/dst.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,108 +42,6 @@
* to dirty as few cache lines as possible in __dst_free().
* As this is not a very strong hint, we dont force an alignment on SMP.
*/
static struct {
spinlock_t lock;
struct dst_entry *list;
unsigned long timer_inc;
unsigned long timer_expires;
} dst_garbage = {
.lock = __SPIN_LOCK_UNLOCKED(dst_garbage.lock),
.timer_inc = DST_GC_MAX,
};
static void dst_gc_task(struct work_struct *work);
static void ___dst_free(struct dst_entry *dst);

static DECLARE_DELAYED_WORK(dst_gc_work, dst_gc_task);

static DEFINE_MUTEX(dst_gc_mutex);
/*
* long lived entries are maintained in this list, guarded by dst_gc_mutex
*/
static struct dst_entry *dst_busy_list;

static void dst_gc_task(struct work_struct *work)
{
int delayed = 0;
int work_performed = 0;
unsigned long expires = ~0L;
struct dst_entry *dst, *next, head;
struct dst_entry *last = &head;

mutex_lock(&dst_gc_mutex);
next = dst_busy_list;

loop:
while ((dst = next) != NULL) {
next = dst->next;
prefetch(&next->next);
cond_resched();
if (likely(atomic_read(&dst->__refcnt))) {
last->next = dst;
last = dst;
delayed++;
continue;
}
work_performed++;

dst = dst_destroy(dst);
if (dst) {
/* NOHASH and still referenced. Unless it is already
* on gc list, invalidate it and add to gc list.
*
* Note: this is temporary. Actually, NOHASH dst's
* must be obsoleted when parent is obsoleted.
* But we do not have state "obsoleted, but
* referenced by parent", so it is right.
*/
if (dst->obsolete > 0)
continue;

___dst_free(dst);
dst->next = next;
next = dst;
}
}

spin_lock_bh(&dst_garbage.lock);
next = dst_garbage.list;
if (next) {
dst_garbage.list = NULL;
spin_unlock_bh(&dst_garbage.lock);
goto loop;
}
last->next = NULL;
dst_busy_list = head.next;
if (!dst_busy_list)
dst_garbage.timer_inc = DST_GC_MAX;
else {
/*
* if we freed less than 1/10 of delayed entries,
* we can sleep longer.
*/
if (work_performed <= delayed/10) {
dst_garbage.timer_expires += dst_garbage.timer_inc;
if (dst_garbage.timer_expires > DST_GC_MAX)
dst_garbage.timer_expires = DST_GC_MAX;
dst_garbage.timer_inc += DST_GC_INC;
} else {
dst_garbage.timer_inc = DST_GC_INC;
dst_garbage.timer_expires = DST_GC_MIN;
}
expires = dst_garbage.timer_expires;
/*
* if the next desired timer is more than 4 seconds in the
* future then round the timer to whole seconds
*/
if (expires > 4*HZ)
expires = round_jiffies_relative(expires);
schedule_delayed_work(&dst_gc_work, expires);
}

spin_unlock_bh(&dst_garbage.lock);
mutex_unlock(&dst_gc_mutex);
}

int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
{
kfree_skb(skb);
Expand Down Expand Up @@ -216,34 +114,6 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
}
EXPORT_SYMBOL(dst_alloc);

static void ___dst_free(struct dst_entry *dst)
{
/* The first case (dev==NULL) is required, when
protocol module is unloaded.
*/
if (dst->dev == NULL || !(dst->dev->flags&IFF_UP)) {
dst->input = dst_discard;
dst->output = dst_discard_out;
}
dst->obsolete = DST_OBSOLETE_DEAD;
}

void __dst_free(struct dst_entry *dst)
{
spin_lock_bh(&dst_garbage.lock);
___dst_free(dst);
dst->next = dst_garbage.list;
dst_garbage.list = dst;
if (dst_garbage.timer_inc > DST_GC_INC) {
dst_garbage.timer_inc = DST_GC_INC;
dst_garbage.timer_expires = DST_GC_MIN;
mod_delayed_work(system_wq, &dst_gc_work,
dst_garbage.timer_expires);
}
spin_unlock_bh(&dst_garbage.lock);
}
EXPORT_SYMBOL(__dst_free);

struct dst_entry *dst_destroy(struct dst_entry * dst)
{
struct dst_entry *child;
Expand Down Expand Up @@ -448,86 +318,3 @@ struct metadata_dst __percpu *metadata_dst_alloc_percpu(u8 optslen, gfp_t flags)
return md_dst;
}
EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);

/* Dirty hack. We did it in 2.2 (in __dst_free),
* we have _very_ good reasons not to repeat
* this mistake in 2.3, but we have no choice
* now. _It_ _is_ _explicit_ _deliberate_
* _race_ _condition_.
*
* Commented and originally written by Alexey.
*/
static void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
int unregister)
{
if (dst->ops->ifdown)
dst->ops->ifdown(dst, dev, unregister);

if (dev != dst->dev)
return;

if (!unregister) {
dst->input = dst_discard;
dst->output = dst_discard_out;
} else {
dst->dev = dev_net(dst->dev)->loopback_dev;
dev_hold(dst->dev);
dev_put(dev);
}
}

static int dst_dev_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct dst_entry *dst, *last = NULL;

switch (event) {
case NETDEV_UNREGISTER_FINAL:
case NETDEV_DOWN:
mutex_lock(&dst_gc_mutex);
for (dst = dst_busy_list; dst; dst = dst->next) {
last = dst;
dst_ifdown(dst, dev, event != NETDEV_DOWN);
}

spin_lock_bh(&dst_garbage.lock);
dst = dst_garbage.list;
dst_garbage.list = NULL;
/* The code in dst_ifdown places a hold on the loopback device.
* If the gc entry processing is set to expire after a lengthy
* interval, this hold can cause netdev_wait_allrefs() to hang
* out and wait for a long time -- until the the loopback
* interface is released. If we're really unlucky, it'll emit
* pr_emerg messages to console too. Reset the interval here,
* so dst cleanups occur in a more timely fashion.
*/
if (dst_garbage.timer_inc > DST_GC_INC) {
dst_garbage.timer_inc = DST_GC_INC;
dst_garbage.timer_expires = DST_GC_MIN;
mod_delayed_work(system_wq, &dst_gc_work,
dst_garbage.timer_expires);
}
spin_unlock_bh(&dst_garbage.lock);

if (last)
last->next = dst;
else
dst_busy_list = dst;
for (; dst; dst = dst->next)
dst_ifdown(dst, dev, event != NETDEV_DOWN);
mutex_unlock(&dst_gc_mutex);
break;
}
return NOTIFY_DONE;
}

static struct notifier_block dst_dev_notifier = {
.notifier_call = dst_dev_event,
.priority = -10, /* must be called after other network notifiers */
};

void __init dst_subsys_init(void)
{
register_netdevice_notifier(&dst_dev_notifier);
}

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