[SCSI] fcoe: Fix module ref count bug by adding NETDEV UNREGISTER handling

Fixes reference counting on fcoe_instance and net_device, and adds
NETDEV_UNREGISTER notifier handling so that you can unload network drivers.
FCoE no longer increments the module use count for the network driver.

On an NETDEV_UNREGISTER event, destroying the FCoE instance is deferred to a
workqueue context to avoid RTNL deadlocks.

Based in part by an earlier patch from John Fastabend

John's patch description:
Currently, the netdev module ref count is not decremented with module_put()
when the module is unloaded while fcoe instances are present. To fix this
removed reference count on netdev module completely and added functionality to
netdev event handling for NETDEV_UNREGISTER events.

This allows fcoe to remove devices cleanly when the netdev module is unloaded
so we no longer need to hold a reference count for the netdev module.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index c9a0346..c0264a9 100644 (file)
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -74,12 +74,13 @@ static int fcoe_link_ok(struct fc_lport *lp);
 
 static struct fc_lport *fcoe_hostlist_lookup(const struct net_device *);
 static int fcoe_hostlist_add(const struct fc_lport *);
-static int fcoe_hostlist_remove(const struct fc_lport *);
 
 static void fcoe_check_wait_queue(struct fc_lport *, struct sk_buff *);
 static int fcoe_device_notification(struct notifier_block *, ulong, void *);
 static void fcoe_dev_setup(void);
 static void fcoe_dev_cleanup(void);
+static struct fcoe_interface *
+       fcoe_hostlist_lookup_port(const struct net_device *dev);
 
 /* notification function from net device */
 static struct notifier_block fcoe_notifier = {
@@ -149,6 +150,7 @@ static int fcoe_fip_recv(struct sk_buff *skb, struct net_device *dev,
  * @netdev : ptr to the associated netdevice struct
  *
  * Returns : 0 for success
+ * Locking: must be called with the RTNL mutex held
  */
 static int fcoe_interface_setup(struct fcoe_interface *fcoe,
                                struct net_device *netdev)
@@ -188,13 +190,11 @@ static int fcoe_interface_setup(struct fcoe_interface *fcoe,
         * or enter promiscuous mode if not capable of listening
         * for multiple unicast MACs.
         */
-       rtnl_lock();
        memcpy(flogi_maddr, (u8[6]) FC_FCOE_FLOGI_MAC, ETH_ALEN);
        dev_unicast_add(netdev, flogi_maddr);
        if (fip->spma)
                dev_unicast_add(netdev, fip->ctl_src_addr);
        dev_mc_add(netdev, FIP_ALL_ENODE_MACS, ETH_ALEN, 0);
-       rtnl_unlock();
 
        /*
         * setup the receive function from ethernet driver
@@ -215,6 +215,7 @@ static int fcoe_interface_setup(struct fcoe_interface *fcoe,
 
 static void fcoe_fip_send(struct fcoe_ctlr *fip, struct sk_buff *skb);
 static void fcoe_update_src_mac(struct fcoe_ctlr *fip, u8 *old, u8 *new);
+static void fcoe_destroy_work(struct work_struct *work);
 
 /**
  * fcoe_interface_create()
@@ -232,6 +233,7 @@ static struct fcoe_interface *fcoe_interface_create(struct net_device *netdev)
                return NULL;
        }
 
+       dev_hold(netdev);
        kref_init(&fcoe->kref);
 
        /*
@@ -249,6 +251,8 @@ static struct fcoe_interface *fcoe_interface_create(struct net_device *netdev)
 /**
  * fcoe_interface_cleanup() - clean up netdev configurations
  * @fcoe:
+ *
+ * Caller must be holding the RTNL mutex
  */
 void fcoe_interface_cleanup(struct fcoe_interface *fcoe)
 {
@@ -266,11 +270,7 @@ void fcoe_interface_cleanup(struct fcoe_interface *fcoe)
        __dev_remove_pack(&fcoe->fip_packet_type);
        synchronize_net();
 
-       /* tear-down the FCoE controller */
-       fcoe_ctlr_destroy(&fcoe->ctlr);
-
        /* Delete secondary MAC addresses */
-       rtnl_lock();
        memcpy(flogi_maddr, (u8[6]) FC_FCOE_FLOGI_MAC, ETH_ALEN);
        dev_unicast_delete(netdev, flogi_maddr);
        if (!is_zero_ether_addr(fip->data_src_addr))
@@ -278,7 +278,6 @@ void fcoe_interface_cleanup(struct fcoe_interface *fcoe)
        if (fip->spma)
                dev_unicast_delete(netdev, fip->ctl_src_addr);
        dev_mc_delete(netdev, FIP_ALL_ENODE_MACS, ETH_ALEN, 0);
-       rtnl_unlock();
 }
 
 /**
@@ -288,10 +287,14 @@ void fcoe_interface_cleanup(struct fcoe_interface *fcoe)
 static void fcoe_interface_release(struct kref *kref)
 {
        struct fcoe_interface *fcoe;
+       struct net_device *netdev;
 
        fcoe = container_of(kref, struct fcoe_interface, kref);
-       fcoe_interface_cleanup(fcoe);
+       netdev = fcoe->netdev;
+       /* tear-down the FCoE controller */
+       fcoe_ctlr_destroy(&fcoe->ctlr);
        kfree(fcoe);
+       dev_put(netdev);
 }
 
 /**
@@ -642,8 +645,7 @@ static void fcoe_if_destroy(struct fc_lport *lport)
        /* Free memory used by statistical counters */
        fc_lport_free_stats(lport);
 
-       /* Release the net_device and Scsi_Host */
-       dev_put(netdev);
+       /* Release the Scsi_Host */
        scsi_host_put(lport->host);
 }
 
@@ -718,7 +720,9 @@ static struct fc_lport *fcoe_if_create(struct fcoe_interface *fcoe,
        }
        lport = shost_priv(shost);
        port = lport_priv(lport);
+       port->lport = lport;
        port->fcoe = fcoe;
+       INIT_WORK(&port->destroy_work, fcoe_destroy_work);
 
        /* configure fc_lport, e.g., em */
        rc = fcoe_lport_config(lport);
@@ -769,7 +773,6 @@ static struct fc_lport *fcoe_if_create(struct fcoe_interface *fcoe,
                goto out_lp_destroy;
        }
 
-       dev_hold(netdev);
        fcoe_interface_get(fcoe);
        return lport;
 
@@ -1530,19 +1533,19 @@ static int fcoe_device_notification(struct notifier_block *notifier,
        struct fc_lport *lp = NULL;
        struct net_device *netdev = ptr;
        struct fcoe_interface *fcoe;
+       struct fcoe_port *port;
        struct fcoe_dev_stats *stats;
        u32 link_possible = 1;
        u32 mfs;
        int rc = NOTIFY_OK;
 
-       read_lock(&fcoe_hostlist_lock);
+       write_lock(&fcoe_hostlist_lock);
        list_for_each_entry(fcoe, &fcoe_hostlist, list) {
                if (fcoe->netdev == netdev) {
                        lp = fcoe->ctlr.lp;
                        break;
                }
        }
-       read_unlock(&fcoe_hostlist_lock);
        if (lp == NULL) {
                rc = NOTIFY_DONE;
                goto out;
@@ -1564,6 +1567,13 @@ static int fcoe_device_notification(struct notifier_block *notifier,
                break;
        case NETDEV_REGISTER:
                break;
+       case NETDEV_UNREGISTER:
+               list_del(&fcoe->list);
+               port = lport_priv(fcoe->ctlr.lp);
+               fcoe_interface_cleanup(fcoe);
+               schedule_work(&port->destroy_work);
+               goto out;
+               break;
        default:
                FCOE_NETDEV_DBG(netdev, "Unknown event %ld "
                                "from netdev netlink\n", event);
@@ -1576,6 +1586,7 @@ static int fcoe_device_notification(struct notifier_block *notifier,
                fcoe_clean_pending_queue(lp);
        }
 out:
+       write_unlock(&fcoe_hostlist_lock);
        return rc;
 }
 
@@ -1600,75 +1611,6 @@ static struct net_device *fcoe_if_to_netdev(const char *buffer)
        return NULL;
 }
 
-/**
- * fcoe_netdev_to_module_owner() - finds out the driver module of the netdev
- * @netdev: the target netdev
- *
- * Returns: ptr to the struct module, NULL for failure
- */
-static struct module *
-fcoe_netdev_to_module_owner(const struct net_device *netdev)
-{
-       struct device *dev;
-
-       if (!netdev)
-               return NULL;
-
-       dev = netdev->dev.parent;
-       if (!dev)
-               return NULL;
-
-       if (!dev->driver)
-               return NULL;
-
-       return dev->driver->owner;
-}
-
-/**
- * fcoe_ethdrv_get() - Hold the Ethernet driver
- * @netdev: the target netdev
- *
- * Holds the Ethernet driver module by try_module_get() for
- * the corresponding netdev.
- *
- * Returns: 0 for success
- */
-static int fcoe_ethdrv_get(const struct net_device *netdev)
-{
-       struct module *owner;
-
-       owner = fcoe_netdev_to_module_owner(netdev);
-       if (owner) {
-               FCOE_NETDEV_DBG(netdev, "Hold driver module %s\n",
-                               module_name(owner));
-               return  try_module_get(owner);
-       }
-       return -ENODEV;
-}
-
-/**
- * fcoe_ethdrv_put() - Release the Ethernet driver
- * @netdev: the target netdev
- *
- * Releases the Ethernet driver module by module_put for
- * the corresponding netdev.
- *
- * Returns: 0 for success
- */
-static int fcoe_ethdrv_put(const struct net_device *netdev)
-{
-       struct module *owner;
-
-       owner = fcoe_netdev_to_module_owner(netdev);
-       if (owner) {
-               FCOE_NETDEV_DBG(netdev, "Release driver module %s\n",
-                               module_name(owner));
-               module_put(owner);
-               return 0;
-       }
-       return -ENODEV;
-}
-
 /**
  * fcoe_destroy() - handles the destroy from sysfs
  * @buffer: expected to be an eth if name
@@ -1678,10 +1620,8 @@ static int fcoe_ethdrv_put(const struct net_device *netdev)
  */
 static int fcoe_destroy(const char *buffer, struct kernel_param *kp)
 {
-       struct net_device *netdev;
        struct fcoe_interface *fcoe;
-       struct fcoe_port *port;
-       struct fc_lport *lport;
+       struct net_device *netdev;
        int rc;
 
        mutex_lock(&fcoe_config_mutex);
@@ -1702,19 +1642,20 @@ static int fcoe_destroy(const char *buffer, struct kernel_param *kp)
                rc = -ENODEV;
                goto out_nodev;
        }
-       /* look for existing lport */
-       lport = fcoe_hostlist_lookup(netdev);
-       if (!lport) {
+
+       write_lock(&fcoe_hostlist_lock);
+       fcoe = fcoe_hostlist_lookup_port(netdev);
+       if (!fcoe) {
+               write_unlock(&fcoe_hostlist_lock);
                rc = -ENODEV;
                goto out_putdev;
        }
-       /* Remove the instance from fcoe's list */
-       fcoe_hostlist_remove(lport);
-       port = lport_priv(lport);
-       fcoe = port->fcoe;
-       fcoe_if_destroy(lport);
-       fcoe_ethdrv_put(netdev);
-       rc = 0;
+       list_del(&fcoe->list);
+       write_unlock(&fcoe_hostlist_lock);
+       rtnl_lock();
+       fcoe_interface_cleanup(fcoe);
+       rtnl_unlock();
+       fcoe_if_destroy(fcoe->ctlr.lp);
 out_putdev:
        dev_put(netdev);
 out_nodev:
@@ -1722,6 +1663,16 @@ out_nodev:
        return rc;
 }
 
+static void fcoe_destroy_work(struct work_struct *work)
+{
+       struct fcoe_port *port;
+
+       port = container_of(work, struct fcoe_port, destroy_work);
+       mutex_lock(&fcoe_config_mutex);
+       fcoe_if_destroy(port->lport);
+       mutex_unlock(&fcoe_config_mutex);
+}
+
 /**
  * fcoe_create() - Handles the create call from sysfs
  * @buffer: expected to be an eth if name
@@ -1749,17 +1700,18 @@ static int fcoe_create(const char *buffer, struct kernel_param *kp)
        }
 #endif
 
+       rtnl_lock();
        netdev = fcoe_if_to_netdev(buffer);
        if (!netdev) {
                rc = -ENODEV;
                goto out_nodev;
        }
+
        /* look for existing lport */
        if (fcoe_hostlist_lookup(netdev)) {
                rc = -EEXIST;
                goto out_putdev;
        }
-       fcoe_ethdrv_get(netdev);
 
        fcoe = fcoe_interface_create(netdev);
        if (!fcoe) {
@@ -1771,8 +1723,8 @@ static int fcoe_create(const char *buffer, struct kernel_param *kp)
        if (IS_ERR(lport)) {
                printk(KERN_ERR "fcoe: Failed to create interface (%s)\n",
                       netdev->name);
-               fcoe_ethdrv_put(netdev);
                rc = -EIO;
+               fcoe_interface_cleanup(fcoe);
                goto out_free;
        }
 
@@ -1798,6 +1750,7 @@ out_free:
 out_putdev:
        dev_put(netdev);
 out_nodev:
+       rtnl_unlock();
        mutex_unlock(&fcoe_config_mutex);
        return rc;
 }
@@ -1972,25 +1925,6 @@ int fcoe_hostlist_add(const struct fc_lport *lport)
        return 0;
 }
 
-/**
- * fcoe_hostlist_remove() - remove a lport from lports list
- * @lp: ptr to the fc_lport to be removed
- *
- * Returns: 0 for success
- */
-int fcoe_hostlist_remove(const struct fc_lport *lport)
-{
-       struct fcoe_interface *fcoe;
-
-       write_lock_bh(&fcoe_hostlist_lock);
-       fcoe = fcoe_hostlist_lookup_port(fcoe_netdev(lport));
-       BUG_ON(!fcoe);
-       list_del(&fcoe->list);
-       write_unlock_bh(&fcoe_hostlist_lock);
-
-       return 0;
-}
-
 /**
  * fcoe_init() - fcoe module loading initialization
  *
@@ -2046,6 +1980,7 @@ static void __exit fcoe_exit(void)
        unsigned int cpu;
        struct fcoe_interface *fcoe, *tmp;
        LIST_HEAD(local_list);
+       struct fcoe_port *port;
 
        mutex_lock(&fcoe_config_mutex);
 
@@ -2058,7 +1993,11 @@ static void __exit fcoe_exit(void)
 
        list_for_each_entry_safe(fcoe, tmp, &local_list, list) {
                list_del(&fcoe->list);
-               fcoe_if_destroy(fcoe->ctlr.lp);
+               port = lport_priv(fcoe->ctlr.lp);
+               rtnl_lock();
+               fcoe_interface_cleanup(fcoe);
+               rtnl_unlock();
+               schedule_work(&port->destroy_work);
        }
 
        unregister_hotcpu_notifier(&fcoe_cpu_notifier);
@@ -2066,9 +2005,14 @@ static void __exit fcoe_exit(void)
        for_each_online_cpu(cpu)
                fcoe_percpu_thread_destroy(cpu);
 
-       /* detach from scsi transport */
-       fcoe_if_exit();
-
        mutex_unlock(&fcoe_config_mutex);
+
+       /* flush any asyncronous interface destroys,
+        * this should happen after the netdev notifier is unregistered */
+       flush_scheduled_work();
+
+       /* detach from scsi transport
+        * must happen after all destroys are done, therefor after the flush */
+       fcoe_if_exit();
 }
 module_exit(fcoe_exit);

diff --git a/drivers/scsi/fcoe/fcoe.h b/drivers/scsi/fcoe/fcoe.h
index ff22928..ce7f60f 100644 (file)
--- a/drivers/scsi/fcoe/fcoe.h
+++ b/drivers/scsi/fcoe/fcoe.h
@@ -93,9 +93,11 @@ struct fcoe_interface {
  */
 struct fcoe_port {
        struct fcoe_interface *fcoe;
+       struct fc_lport *lport;
        struct sk_buff_head fcoe_pending_queue;
        u8      fcoe_pending_queue_active;
        struct timer_list timer;                /* queue timer */
+       struct work_struct destroy_work;        /* to prevent rtnl deadlocks */
 };
 
 #define fcoe_from_ctlr(fip) container_of(fip, struct fcoe_interface, ctlr)