Re: [PATCH] (2/8) Eliminate brlock for packet_type

From: Stephen Hemminger (shemminger@osdl.org)
Date: Tue Mar 11 2003 - 19:25:48 EST


On Tue, 2003-03-11 at 16:20, David S. Miller wrote:
> From: Stephen Hemminger <shemminger@osdl.org>
> Date: 11 Mar 2003 16:14:40 -0800
>
> Replace linked list for packet_type with brlock with list macros and RCU.
>
> Then why is a VLAN patch attached?

Little pieces breed confusion...this is the right piece.

diff -urN -X dontdiff linux-2.5.64/include/linux/netdevice.h linux-2.5-nobrlock/include/linux/netdevice.h
--- linux-2.5.64/include/linux/netdevice.h 2003-03-11 09:08:00.000000000 -0800
+++ linux-2.5-nobrlock/include/linux/netdevice.h 2003-03-11 14:15:17.000000000 -0800
@@ -452,7 +452,7 @@
         int (*func) (struct sk_buff *, struct net_device *,
                                          struct packet_type *);
         void *data; /* Private to the packet type */
- struct packet_type *next;
+ struct list_head packet_list;
 };
 
 
diff -urN -X dontdiff linux-2.5.64/net/core/dev.c linux-2.5-nobrlock/net/core/dev.c
--- linux-2.5.64/net/core/dev.c 2003-03-11 09:08:01.000000000 -0800
+++ linux-2.5-nobrlock/net/core/dev.c 2003-03-11 14:37:36.000000000 -0800
@@ -90,7 +90,6 @@
 #include <linux/etherdevice.h>
 #include <linux/notifier.h>
 #include <linux/skbuff.h>
-#include <linux/brlock.h>
 #include <net/sock.h>
 #include <linux/rtnetlink.h>
 #include <linux/proc_fs.h>
@@ -170,8 +169,11 @@
  * 86DD IPv6
  */
 
-static struct packet_type *ptype_base[16]; /* 16 way hashed list */
-static struct packet_type *ptype_all; /* Taps */
+static spinlock_t ptype_lock = SPIN_LOCK_UNLOCKED;
+static struct list_head ptype_base[16]; /* 16 way hashed list */
+static struct list_head ptype_all; /* Taps */
+
+static spinlock_t master_lock = SPIN_LOCK_UNLOCKED;
 
 #ifdef OFFLINE_SAMPLE
 static void sample_queue(unsigned long dummy);
@@ -203,7 +205,6 @@
 
 static struct subsystem net_subsys;
 
-
 /*******************************************************************************
 
                 Protocol management and registration routines
@@ -245,8 +246,7 @@
 {
         int hash;
 
- br_write_lock_bh(BR_NETPROTO_LOCK);
-
+ spin_lock_bh(&ptype_lock);
 #ifdef CONFIG_NET_FASTROUTE
         /* Hack to detect packet socket */
         if (pt->data && (long)(pt->data) != 1) {
@@ -256,14 +256,12 @@
 #endif
         if (pt->type == htons(ETH_P_ALL)) {
                 netdev_nit++;
- pt->next = ptype_all;
- ptype_all = pt;
+ list_add_rcu(&pt->packet_list, &ptype_all);
         } else {
                 hash = ntohs(pt->type) & 15;
- pt->next = ptype_base[hash];
- ptype_base[hash] = pt;
+ list_add_rcu(&pt->packet_list, &ptype_base[hash]);
         }
- br_write_unlock_bh(BR_NETPROTO_LOCK);
+ spin_unlock_bh(&ptype_lock);
 }
 
 extern void linkwatch_run_queue(void);
@@ -279,29 +277,30 @@
  */
 void dev_remove_pack(struct packet_type *pt)
 {
- struct packet_type **pt1;
-
- br_write_lock_bh(BR_NETPROTO_LOCK);
+ struct list_head *head, *pelem;
 
- if (pt->type == htons(ETH_P_ALL)) {
- netdev_nit--;
- pt1 = &ptype_all;
- } else
- pt1 = &ptype_base[ntohs(pt->type) & 15];
-
- for (; *pt1; pt1 = &((*pt1)->next)) {
- if (pt == *pt1) {
- *pt1 = pt->next;
+ if (pt->type == htons(ETH_P_ALL))
+ head = &ptype_all;
+ else
+ head = &ptype_base[ntohs(pt->type) & 15];
+
+ spin_lock_bh(&ptype_lock);
+ list_for_each(pelem, head) {
+ if (list_entry(pelem, struct packet_type, packet_list) == pt) {
+ list_del(pelem);
 #ifdef CONFIG_NET_FASTROUTE
                         if (pt->data)
                                 netdev_fastroute_obstacles--;
 #endif
+ if (pt->type == htons(ETH_P_ALL))
+ netdev_nit--;
                         goto out;
                 }
         }
         printk(KERN_WARNING "dev_remove_pack: %p not found.\n", pt);
-out:
- br_write_unlock_bh(BR_NETPROTO_LOCK);
+
+ out:
+ spin_unlock_bh(&ptype_lock);
 }
 
 /******************************************************************************
@@ -896,11 +895,13 @@
 
 void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 {
- struct packet_type *ptype;
+ struct list_head *plist;
         do_gettimeofday(&skb->stamp);
 
- br_read_lock(BR_NETPROTO_LOCK);
- for (ptype = ptype_all; ptype; ptype = ptype->next) {
+ rcu_read_lock();
+ list_for_each_rcu(plist, &ptype_all) {
+ struct packet_type *ptype
+ = list_entry(plist, struct packet_type, packet_list);
                 /* Never send packets back to the socket
                  * they originated from - MvS (miquels@drinkel.ow.org)
                  */
@@ -930,7 +931,7 @@
                         ptype->func(skb2, skb->dev, ptype);
                 }
         }
- br_read_unlock(BR_NETPROTO_LOCK);
+ rcu_read_unlock();
 }
 
 /* Calculate csum in the case, when packet is misrouted.
@@ -1423,6 +1424,7 @@
 
 int netif_receive_skb(struct sk_buff *skb)
 {
+ struct list_head *pcur;
         struct packet_type *ptype, *pt_prev;
         int ret = NET_RX_DROP;
         unsigned short type = skb->protocol;
@@ -1443,8 +1445,10 @@
 
         skb->h.raw = skb->nh.raw = skb->data;
 
+ rcu_read_lock();
         pt_prev = NULL;
- for (ptype = ptype_all; ptype; ptype = ptype->next) {
+ list_for_each_rcu(pcur, &ptype_all) {
+ ptype = list_entry(pcur, struct packet_type, packet_list);
                 if (!ptype->dev || ptype->dev == skb->dev) {
                         if (pt_prev) {
                                 if (!pt_prev->data) {
@@ -1476,7 +1480,9 @@
         }
 #endif
 
- for (ptype = ptype_base[ntohs(type) & 15]; ptype; ptype = ptype->next) {
+ list_for_each_rcu(pcur, &ptype_base[ntohs(type) & 15]) {
+ ptype = list_entry(pcur, struct packet_type, packet_list);
+
                 if (ptype->type == type &&
                     (!ptype->dev || ptype->dev == skb->dev)) {
                         if (pt_prev) {
@@ -1506,6 +1512,7 @@
                  */
                 ret = NET_RX_DROP;
         }
+ rcu_read_unlock();
 
         return ret;
 }
@@ -1580,7 +1587,7 @@
         unsigned long start_time = jiffies;
         int budget = netdev_max_backlog;
 
- br_read_lock(BR_NETPROTO_LOCK);
+ preempt_disable();
         local_irq_disable();
 
         while (!list_empty(&queue->poll_list)) {
@@ -1609,7 +1616,7 @@
         }
 out:
         local_irq_enable();
- br_read_unlock(BR_NETPROTO_LOCK);
+ preempt_enable();
         return;
 
 softnet_break:
@@ -1925,6 +1932,10 @@
 #define dev_proc_init() 0
 #endif /* CONFIG_PROC_FS */
 
+static RCU_HEAD(netdev_master_rcu);
+static void unset_old_master(void *arg) {
+ dev_put((struct net_device *) arg);
+}
 
 /**
  * netdev_set_master - set up master/slave pair
@@ -1943,18 +1954,20 @@
 
         ASSERT_RTNL();
 
+ spin_lock_bh(&master_lock);
         if (master) {
- if (old)
+ if (old) {
+ spin_unlock_bh(&master_lock);
                         return -EBUSY;
+ }
                 dev_hold(master);
         }
 
- br_write_lock_bh(BR_NETPROTO_LOCK);
         slave->master = master;
- br_write_unlock_bh(BR_NETPROTO_LOCK);
+ spin_unlock_bh(&master_lock);
 
- if (old)
- dev_put(old);
+ if (old)
+ call_rcu(&netdev_master_rcu, unset_old_master, old);
 
         if (master)
                 slave->flags |= IFF_SLAVE;
@@ -1962,6 +1975,7 @@
                 slave->flags &= ~IFF_SLAVE;
 
         rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE);
+
         return 0;
 }
 
@@ -2646,10 +2660,7 @@
                 return -ENODEV;
         }
 
- /* Synchronize to net_rx_action. */
- br_write_lock_bh(BR_NETPROTO_LOCK);
- br_write_unlock_bh(BR_NETPROTO_LOCK);
-
+ synchronize_kernel();
 
 #ifdef CONFIG_NET_FASTROUTE
         dev_clear_fastroute(dev);
@@ -2755,7 +2766,6 @@
         return 0;
 }
 
-
 /*
  * Initialize the DEV module. At boot time this walks the device list and
  * unhooks any devices that fail to initialise (normally hardware not
@@ -2786,6 +2796,11 @@
         if (dev_proc_init())
                 goto out;
 
+ /* Initialize packet type chains */
+ INIT_LIST_HEAD(&ptype_all);
+ for (i = 0; i < ARRAY_SIZE(ptype_base); i++)
+ INIT_LIST_HEAD(&ptype_base[i]);
+
         subsystem_register(&net_subsys);
 
 #ifdef CONFIG_NET_DIVERT

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This archive was generated by hypermail 2b29 : Sat Mar 15 2003 - 22:00:28 EST