[PATCH] (2/4) Support for lots of netdev's -- hash name
From: Stephen Hemminger <hidden>
Date: 2004-02-06 18:20:46
Hash the network device names for faster lookup when there are 1000's of network devices. Need to keep track of tail of dev_base linked list, for fast insertion, since no longer need to walk whole list. Resend of the patchset to support a large number of network devices efficiently with feedback applied, and rediff'd against 2.6.2 diff -Nru a/include/linux/netdevice.h b/include/linux/netdevice.h
--- a/include/linux/netdevice.h Thu Feb 5 15:17:15 2004
+++ b/include/linux/netdevice.h Thu Feb 5 15:17:15 2004@@ -375,6 +375,8 @@ atomic_t refcnt; /* delayed register/unregister */ struct list_head todo_list; + /* device name hash chain */ + struct hlist_node name_hlist; /* register/unregister state machine */ enum { NETREG_UNINITIALIZED=0,
diff -Nru a/net/core/dev.c b/net/core/dev.c
--- a/net/core/dev.c Thu Feb 5 15:17:15 2004
+++ b/net/core/dev.c Thu Feb 5 15:17:15 2004@@ -180,11 +180,21 @@ * semaphore held. */ struct net_device *dev_base; +struct net_device **dev_tail = &dev_base; rwlock_t dev_base_lock = RW_LOCK_UNLOCKED; EXPORT_SYMBOL(dev_base); EXPORT_SYMBOL(dev_base_lock); +#define NETDEV_HASHBITS 8 +static struct hlist_head dev_name_head[1<<NETDEV_HASHBITS]; + +static inline struct hlist_head *dev_name_hash(const char *name) +{ + unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ)); + return &dev_name_head[hash & ((1<<NETDEV_HASHBITS)-1)]; +} + /* * Our notifier list */
@@ -468,12 +478,15 @@ struct net_device *__dev_get_by_name(const char *name) { - struct net_device *dev; + struct hlist_node *p; - for (dev = dev_base; dev; dev = dev->next) + hlist_for_each(p, dev_name_hash(name)) { + struct net_device *dev + = hlist_entry(p, struct net_device, name_hlist); if (!strncmp(dev->name, name, IFNAMSIZ)) - break; - return dev; + return dev; + } + return NULL; } /**
@@ -754,6 +767,9 @@ else strlcpy(dev->name, newname, IFNAMSIZ); + hlist_del(&dev->name_hlist); + hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name)); + class_device_rename(&dev->class_dev, dev->name); notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev); return 0;
@@ -2742,7 +2758,8 @@ int register_netdevice(struct net_device *dev) { - struct net_device *d, **dp; + struct hlist_head *head; + struct hlist_node *p; int ret; BUG_ON(dev_boot_phase);
@@ -2783,13 +2800,17 @@ if (dev->iflink == -1) dev->iflink = dev->ifindex; - /* Check for existence, and append to tail of chain */ - ret = -EEXIST; - for (dp = &dev_base; (d = *dp) != NULL; dp = &d->next) { - if (d == dev || !strcmp(d->name, dev->name)) - goto out_err; - } - + /* Check for existence of name */ + head = dev_name_hash(dev->name); + hlist_for_each(p, head) { + struct net_device *d + = hlist_entry(p, struct net_device, name_hlist); + if (!strncmp(d->name, dev->name, IFNAMSIZ)) { + ret = -EEXIST; + goto out_err; + } + } + /* Fix illegal SG+CSUM combinations. */ if ((dev->features & NETIF_F_SG) && !(dev->features & (NETIF_F_IP_CSUM |
@@ -2818,7 +2839,9 @@ dev->next = NULL; dev_init_scheduler(dev); write_lock_bh(&dev_base_lock); - *dp = dev; + *dev_tail = dev; + dev_tail = &dev->next; + hlist_add_head(&dev->name_hlist, head); dev_hold(dev); dev->reg_state = NETREG_REGISTERING; write_unlock_bh(&dev_base_lock);
@@ -3040,6 +3063,9 @@ for (dp = &dev_base; (d = *dp) != NULL; dp = &d->next) { if (d == dev) { write_lock_bh(&dev_base_lock); + hlist_del(&dev->name_hlist); + if (dev_tail == &dev->next) + dev_tail = dp; *dp = d->next; write_unlock_bh(&dev_base_lock); break;
@@ -3115,6 +3141,9 @@ INIT_LIST_HEAD(&ptype_all); for (i = 0; i < 16; i++) INIT_LIST_HEAD(&ptype_base[i]); + + for (i = 0; i < ARRAY_SIZE(dev_name_head); i++) + INIT_HLIST_HEAD(&dev_name_head[i]); /* * Initialise the packet receive queues.