[PATCH 2.6.5] (8/9) bridge - support lots of 1k ports

[Stephen Hemminger <shemminger@xxxxxxxx>]

Support >256 ports on a bridge.  Use the suggestion of reducing
the number of bits of priority and increasing the number of bits
for port number.

Easy to increase to even larger if necessary.

diff -Nru a/net/bridge/br_if.c b/net/bridge/br_if.c
--- a/net/bridge/br_if.c        Tue Apr 13 13:16:56 2004
+++ b/net/bridge/br_if.c        Tue Apr 13 13:16:56 2004
@@ -24,9 +24,6 @@
 
 #include "br_private.h"
 
-/* Limited to 256 ports because of STP protocol pdu */
-#define  BR_MAX_PORTS  256
-
 /*
  * Determine initial path cost based on speed.
  * using recommendations from 802.1d standard
@@ -166,23 +163,27 @@
        return br;
 }
 
-static int free_port(struct net_bridge *br)
+/* find an available port number */
+static int find_portno(struct net_bridge *br)
 {
        int index;
        struct net_bridge_port *p;
-       long inuse[BR_MAX_PORTS/(sizeof(long)*8)];
+       unsigned long *inuse;
+
+       inuse = kmalloc(BITS_TO_LONGS(BR_MAX_PORTS)*sizeof(unsigned long),
+                       GFP_ATOMIC);
+       if (!inuse)
+               return -ENOMEM;
 
-       /* find free port number */
-       memset(inuse, 0, sizeof(inuse));
+       CLEAR_BITMAP(inuse, BR_MAX_PORTS);
+       set_bit(0, inuse);      /* zero is reserved */
        list_for_each_entry(p, &br->port_list, list) {
                set_bit(p->port_no, inuse);
        }
-
        index = find_first_zero_bit(inuse, BR_MAX_PORTS);
-       if (index >= BR_MAX_PORTS)
-               return -EXFULL;
+       kfree(inuse);
 
-       return index;
+       return (index >= BR_MAX_PORTS) ? -EXFULL : index;
 }
 
 /* called under bridge lock */
@@ -193,7 +194,7 @@
        int index;
        struct net_bridge_port *p;
        
-       index = free_port(br);
+       index = find_portno(br);
        if (index < 0)
                return ERR_PTR(index);
 
@@ -206,7 +207,7 @@
        dev_hold(dev);
        p->dev = dev;
        p->path_cost = cost;
-       p->priority = 0x80;
+       p->priority = 0x8000 >> BR_PORT_BITS;
        dev->br_port = p;
        p->port_no = index;
        br_init_port(p);
diff -Nru a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
--- a/net/bridge/br_ioctl.c     Tue Apr 13 13:16:56 2004
+++ b/net/bridge/br_ioctl.c     Tue Apr 13 13:16:56 2004
@@ -91,9 +91,15 @@
 
        case BRCTL_GET_PORT_LIST:
        {
-               int num = arg1 ? arg1 : 256;    /* compatiablity */
-               int ret = 0;
-               int *indices;
+               int num, *indices;
+
+               num = arg1;
+               if (num < 0)
+                       return -EINVAL;
+               if (num == 0)
+                       num = 256;
+               if (num > BR_MAX_PORTS)
+                       num = BR_MAX_PORTS;
 
                indices = kmalloc(num*sizeof(int), GFP_KERNEL);
                if (indices == NULL)
@@ -103,9 +109,9 @@
 
                br_get_port_ifindices(br, indices, num);
                if (copy_to_user((void *)arg0, indices, num*sizeof(int)))
-                       ret =  -EFAULT;
+                       num =  -EFAULT;
                kfree(indices);
-               return ret;
+               return num;
        }
 
        case BRCTL_SET_BRIDGE_FORWARD_DELAY:
@@ -204,6 +210,9 @@
 
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
+
+               if (arg1 >= (1<<(16-BR_PORT_BITS)))
+                       return -ERANGE;
 
                spin_lock_bh(&br->lock);
                if ((p = br_get_port(br, arg0)) == NULL) 
diff -Nru a/net/bridge/br_private.h b/net/bridge/br_private.h
--- a/net/bridge/br_private.h   Tue Apr 13 13:16:56 2004
+++ b/net/bridge/br_private.h   Tue Apr 13 13:16:56 2004
@@ -24,6 +24,9 @@
 
 #define BR_HOLD_TIME (1*HZ)
 
+#define BR_PORT_BITS   10
+#define BR_MAX_PORTS   (1<<BR_PORT_BITS)
+
 typedef struct bridge_id bridge_id;
 typedef struct mac_addr mac_addr;
 typedef __u16 port_id;
diff -Nru a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
--- a/net/bridge/br_stp_if.c    Tue Apr 13 13:16:56 2004
+++ b/net/bridge/br_stp_if.c    Tue Apr 13 13:16:56 2004
@@ -19,15 +19,21 @@
 #include "br_private.h"
 #include "br_private_stp.h"
 
-static inline __u16 br_make_port_id(const struct net_bridge_port *p)
+
+/* Port id is composed of priority and port number.
+ * NB: least significant bits of priority are dropped to
+ *     make room for more ports.
+ */
+static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
 {
-       return (p->priority << 8) | p->port_no;
+       return ((u16)priority << BR_PORT_BITS) 
+               | (port_no & ((1<<BR_PORT_BITS)-1));
 }
 
 /* called under bridge lock */
 void br_init_port(struct net_bridge_port *p)
 {
-       p->port_id = br_make_port_id(p);
+       p->port_id = br_make_port_id(p->priority, p->port_no);
        br_become_designated_port(p);
        p->state = BR_STATE_BLOCKING;
        p->topology_change_ack = 0;
@@ -185,15 +191,13 @@
 /* called under bridge lock */
 void br_stp_set_port_priority(struct net_bridge_port *p, u8 newprio)
 {
-       __u16 new_port_id;
-
-       p->priority = newprio & 0xFF;
-       new_port_id = br_make_port_id(p);
+       port_id new_port_id = br_make_port_id(newprio, p->port_no);
 
        if (br_is_designated_port(p))
                p->designated_port = new_port_id;
 
        p->port_id = new_port_id;
+       p->priority = newprio;
        if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
            p->port_id < p->designated_port) {
                br_become_designated_port(p);