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