aboutsummaryrefslogtreecommitdiff
path: root/net/core/dst.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-11 19:40:14 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-11 19:40:14 -0700
commit038a5008b2f395c85e6e71d6ddf3c684e7c405b0 (patch)
tree4735eab577e97e5a22c3141e3f60071c8065585e /net/core/dst.c
parentdd6d1844af33acb4edd0a40b1770d091a22c94be (diff)
parent266918303226cceac7eca38ced30f15f277bd89c (diff)
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (867 commits) [SKY2]: status polling loop (post merge) [NET]: Fix NAPI completion handling in some drivers. [TCP]: Limit processing lost_retrans loop to work-to-do cases [TCP]: Fix lost_retrans loop vs fastpath problems [TCP]: No need to re-count fackets_out/sacked_out at RTO [TCP]: Extract tcp_match_queue_to_sack from sacktag code [TCP]: Kill almost unused variable pcount from sacktag [TCP]: Fix mark_head_lost to ignore R-bit when trying to mark L [TCP]: Add bytes_acked (ABC) clearing to FRTO too [IPv6]: Update setsockopt(IPV6_MULTICAST_IF) to support RFC 3493, try2 [NETFILTER]: x_tables: add missing ip6t_modulename aliases [NETFILTER]: nf_conntrack_tcp: fix connection reopening [QETH]: fix qeth_main.c [NETLINK]: fib_frontend build fixes [IPv6]: Export userland ND options through netlink (RDNSS support) [9P]: build fix with !CONFIG_SYSCTL [NET]: Fix dev_put() and dev_hold() comments [NET]: make netlink user -> kernel interface synchronious [NET]: unify netlink kernel socket recognition [NET]: cleanup 3rd argument in netlink_sendskb ... Fix up conflicts manually in Documentation/feature-removal-schedule.txt and my new least favourite crap, the "mod_devicetable" support in the files include/linux/mod_devicetable.h and scripts/mod/file2alias.c. (The latter files seem to be explicitly _designed_ to get conflicts when different subsystems work with them - that have an absolutely horrid lack of subsystem separation!) Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/core/dst.c')
-rw-r--r--net/core/dst.c202
1 files changed, 131 insertions, 71 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
index c6a05879d58..16958e64e57 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -9,59 +9,84 @@
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/workqueue.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/string.h>
#include <linux/types.h>
+#include <net/net_namespace.h>
+#include <net/net_namespace.h>
#include <net/dst.h>
-/* Locking strategy:
- * 1) Garbage collection state of dead destination cache
- * entries is protected by dst_lock.
- * 2) GC is run only from BH context, and is the only remover
- * of entries.
- * 3) Entries are added to the garbage list from both BH
- * and non-BH context, so local BH disabling is needed.
- * 4) All operations modify state, so a spinlock is used.
+/*
+ * Theory of operations:
+ * 1) We use a list, protected by a spinlock, to add
+ * new entries from both BH and non-BH context.
+ * 2) In order to keep spinlock held for a small delay,
+ * we use a second list where are stored long lived
+ * entries, that are handled by the garbage collect thread
+ * fired by a workqueue.
+ * 3) This list is guarded by a mutex,
+ * so that the gc_task and dst_dev_event() can be synchronized.
*/
-static struct dst_entry *dst_garbage_list;
#if RT_CACHE_DEBUG >= 2
static atomic_t dst_total = ATOMIC_INIT(0);
#endif
-static DEFINE_SPINLOCK(dst_lock);
-static unsigned long dst_gc_timer_expires;
-static unsigned long dst_gc_timer_inc = DST_GC_MAX;
-static void dst_run_gc(unsigned long);
+/*
+ * We want to keep lock & list close together
+ * 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 DEFINE_TIMER(dst_gc_timer, dst_run_gc, DST_GC_MIN, 0);
+static DECLARE_DELAYED_WORK(dst_gc_work, dst_gc_task);
-static void dst_run_gc(unsigned long dummy)
+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;
- struct dst_entry * dst, **dstp;
+ int work_performed = 0;
+ unsigned long expires = ~0L;
+ struct dst_entry *dst, *next, head;
+ struct dst_entry *last = &head;
+#if RT_CACHE_DEBUG >= 2
+ ktime_t time_start = ktime_get();
+ struct timespec elapsed;
+#endif
- if (!spin_trylock(&dst_lock)) {
- mod_timer(&dst_gc_timer, jiffies + HZ/10);
- return;
- }
+ mutex_lock(&dst_gc_mutex);
+ next = dst_busy_list;
- del_timer(&dst_gc_timer);
- dstp = &dst_garbage_list;
- work_performed = 0;
- while ((dst = *dstp) != NULL) {
- if (atomic_read(&dst->__refcnt)) {
- dstp = &dst->next;
+loop:
+ while ((dst = next) != NULL) {
+ next = dst->next;
+ prefetch(&next->next);
+ if (likely(atomic_read(&dst->__refcnt))) {
+ last->next = dst;
+ last = dst;
delayed++;
continue;
}
- *dstp = dst->next;
- work_performed = 1;
+ work_performed++;
dst = dst_destroy(dst);
if (dst) {
@@ -77,38 +102,56 @@ static void dst_run_gc(unsigned long dummy)
continue;
___dst_free(dst);
- dst->next = *dstp;
- *dstp = dst;
- dstp = &dst->next;
+ dst->next = next;
+ next = dst;
}
}
- if (!dst_garbage_list) {
- dst_gc_timer_inc = DST_GC_MAX;
- goto out;
+
+ spin_lock_bh(&dst_garbage.lock);
+ next = dst_garbage.list;
+ if (next) {
+ dst_garbage.list = NULL;
+ spin_unlock_bh(&dst_garbage.lock);
+ goto loop;
}
- if (!work_performed) {
- if ((dst_gc_timer_expires += dst_gc_timer_inc) > DST_GC_MAX)
- dst_gc_timer_expires = DST_GC_MAX;
- dst_gc_timer_inc += DST_GC_INC;
- } else {
- dst_gc_timer_inc = DST_GC_INC;
- dst_gc_timer_expires = DST_GC_MIN;
+ 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);
#if RT_CACHE_DEBUG >= 2
- printk("dst_total: %d/%d %ld\n",
- atomic_read(&dst_total), delayed, dst_gc_timer_expires);
+ elapsed = ktime_to_timespec(ktime_sub(ktime_get(), time_start));
+ printk(KERN_DEBUG "dst_total: %d delayed: %d work_perf: %d"
+ " expires: %lu elapsed: %lu us\n",
+ atomic_read(&dst_total), delayed, work_performed,
+ expires,
+ elapsed.tv_sec * USEC_PER_SEC + elapsed.tv_nsec / NSEC_PER_USEC);
#endif
- /* if the next desired timer is more than 4 seconds in the future
- * then round the timer to whole seconds
- */
- if (dst_gc_timer_expires > 4*HZ)
- mod_timer(&dst_gc_timer,
- round_jiffies(jiffies + dst_gc_timer_expires));
- else
- mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);
-
-out:
- spin_unlock(&dst_lock);
}
static int dst_discard(struct sk_buff *skb)
@@ -153,16 +196,16 @@ static void ___dst_free(struct dst_entry * dst)
void __dst_free(struct dst_entry * dst)
{
- spin_lock_bh(&dst_lock);
+ spin_lock_bh(&dst_garbage.lock);
___dst_free(dst);
- dst->next = dst_garbage_list;
- dst_garbage_list = dst;
- if (dst_gc_timer_inc > DST_GC_INC) {
- dst_gc_timer_inc = DST_GC_INC;
- dst_gc_timer_expires = DST_GC_MIN;
- mod_timer(&dst_gc_timer, jiffies + dst_gc_timer_expires);
+ 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;
+ schedule_delayed_work(&dst_gc_work, dst_garbage.timer_expires);
}
- spin_unlock_bh(&dst_lock);
+ spin_unlock_bh(&dst_garbage.lock);
}
struct dst_entry *dst_destroy(struct dst_entry * dst)
@@ -236,13 +279,13 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
if (!unregister) {
dst->input = dst->output = dst_discard;
} else {
- dst->dev = &loopback_dev;
- dev_hold(&loopback_dev);
+ dst->dev = init_net.loopback_dev;
+ dev_hold(dst->dev);
dev_put(dev);
if (dst->neighbour && dst->neighbour->dev == dev) {
- dst->neighbour->dev = &loopback_dev;
+ dst->neighbour->dev = init_net.loopback_dev;
dev_put(dev);
- dev_hold(&loopback_dev);
+ dev_hold(dst->neighbour->dev);
}
}
}
@@ -250,16 +293,33 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
static int dst_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
- struct dst_entry *dst;
+ struct dst_entry *dst, *last = NULL;
+
+ if (dev->nd_net != &init_net)
+ return NOTIFY_DONE;
switch (event) {
case NETDEV_UNREGISTER:
case NETDEV_DOWN:
- spin_lock_bh(&dst_lock);
- for (dst = dst_garbage_list; dst; dst = dst->next) {
+ 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;
+ 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);
}
- spin_unlock_bh(&dst_lock);
+ mutex_unlock(&dst_gc_mutex);
break;
}
return NOTIFY_DONE;