bonding: remove bonding read/write semaphore

The whole read/write semaphore locking can be removed. It doesn't add any
protection that isn't already done by using the RTNL mutex properly.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 36 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 99ddd283e15e..23b832ffe7a9 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3489,10 +3489,10 @@ static int bond_event_changename(struct bonding *bond)
 {
         bond_remove_proc_entry(bond);
         bond_create_proc_entry(bond);
-        down_write(&(bonding_rwsem));
+
         bond_destroy_sysfs_entry(bond);
         bond_create_sysfs_entry(bond);
-        up_write(&(bonding_rwsem));
+
         return NOTIFY_DONE;
 }
 
@@ -4015,7 +4015,6 @@ static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd
                 return -EPERM;
         }
 
-        down_write(&(bonding_rwsem));
         slave_dev = dev_get_by_name(&init_net, ifr->ifr_slave);
 
         pr_debug("slave_dev=%p: \n", slave_dev);
@@ -4048,7 +4047,6 @@ static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd
                 dev_put(slave_dev);
         }
 
-        up_write(&(bonding_rwsem));
         return res;
 }
 
@@ -5123,8 +5121,6 @@ int bond_create(const char *name)
         int res;
 
         rtnl_lock();
-        down_write(&bonding_rwsem);
-
         /* Check to see if the bond already exists. */
         if (name) {
                 list_for_each_entry(bond, &bond_dev_list, bond_list)
@@ -5173,24 +5169,20 @@ int bond_create(const char *name)
                 goto out_bond;
         }
 
-        up_write(&bonding_rwsem);
-        rtnl_unlock(); /* allows sysfs registration of net device */
         res = bond_create_sysfs_entry(netdev_priv(bond_dev));
         if (res < 0)
                 goto out_unreg;
 
+        rtnl_unlock();
         return 0;
 
 out_unreg:
-        rtnl_lock();
-        down_write(&bonding_rwsem);
         unregister_netdevice(bond_dev);
 out_bond:
         bond_deinit(bond_dev);
 out_netdev:
         free_netdev(bond_dev);
 out_rtnl:
-        up_write(&bonding_rwsem);
         rtnl_unlock();
         return res;
 }
@@ -5209,8 +5201,6 @@ static int __init bonding_init(void)
 
         bond_create_proc_dir();
 
-        init_rwsem(&bonding_rwsem);
-
         for (i = 0; i < max_bonds; i++) {
                 res = bond_create(NULL);
                 if (res)
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 1172fe649352..8041b6793532 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -44,20 +44,6 @@
 /*---------------------------- Declarations -------------------------------*/
 
 static int expected_refcount = -1;
-/*--------------------------- Data Structures -----------------------------*/
-
-/* Bonding sysfs lock.  Why can't we just use the subsystem lock?
- * Because kobject_register tries to acquire the subsystem lock.  If
- * we already hold the lock (which we would if the user was creating
- * a new bond through the sysfs interface), we deadlock.
- * This lock is only needed when deleting a bond - we need to make sure
- * that we don't collide with an ongoing ioctl.
- */
-
-struct rw_semaphore bonding_rwsem;
-
-
-
 
 /*------------------------------ Functions --------------------------------*/
 
@@ -70,7 +56,7 @@ static ssize_t bonding_show_bonds(struct class *cls, char *buf)
         int res = 0;
         struct bonding *bond;
 
-        down_read(&(bonding_rwsem));
+        rtnl_lock();
 
         list_for_each_entry(bond, &bond_dev_list, bond_list) {
                 if (res > (PAGE_SIZE - IFNAMSIZ)) {
@@ -84,7 +70,8 @@ static ssize_t bonding_show_bonds(struct class *cls, char *buf)
         }
         if (res)
                 buf[res-1] = '\n'; /* eat the leftover space */
-        up_read(&(bonding_rwsem));
+
+        rtnl_unlock();
         return res;
 }
 
@@ -122,7 +109,6 @@ static ssize_t bonding_store_bonds(struct class *cls, const char *buffer, size_t
 
         if (command[0] == '-') {
                 rtnl_lock();
-                down_write(&bonding_rwsem);
 
                 list_for_each_entry(bond, &bond_dev_list, bond_list)
                         if (strnicmp(bond->dev->name, ifname, IFNAMSIZ) == 0) {
@@ -157,7 +143,6 @@ err_no_cmd:
         return -EPERM;
 
 out_unlock:
-        up_write(&bonding_rwsem);
         rtnl_unlock();
 
         /* Always return either count or an error.  If you return 0, you'll
@@ -253,7 +238,6 @@ static ssize_t bonding_store_slaves(struct device *d,
 
         if (!rtnl_trylock())
                 return restart_syscall();
-        down_write(&(bonding_rwsem));
 
         sscanf(buffer, "%16s", command); /* IFNAMSIZ*/
         ifname = command + 1;
@@ -357,7 +341,6 @@ err_no_cmd:
         ret = -EPERM;
 
 out:
-        up_write(&(bonding_rwsem));
         rtnl_unlock();
         return ret;
 }
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index a6efa0963717..af81e9b7fe34 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -351,9 +351,6 @@ extern const struct bond_parm_tbl arp_validate_tbl[];
 extern const struct bond_parm_tbl fail_over_mac_tbl[];
 extern struct bond_parm_tbl ad_select_tbl[];
 
-/* exported from bond_sysfs.c */
-extern struct rw_semaphore bonding_rwsem;
-
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 void bond_send_unsolicited_na(struct bonding *bond);
 void bond_register_ipv6_notifier(void);