staging: most: net: hold used net device

This adds the dev_hold and dev_put calls to the functions
aim_resume_tx_channel, aim_rx_data and on_netinfo to postpone the
unregistration of the used net device.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/most/aim-network/networking.c b/drivers/staging/most/aim-network/networking.c
index 217265cbf03bfcc63466099855a31efd475f9d9e..4c259c20048f7a189af01ec3454683545d724a3c 100644 (file)
--- a/drivers/staging/most/aim-network/networking.c
+++ b/drivers/staging/most/aim-network/networking.c
@@ -73,7 +73,7 @@ struct net_dev_context {
 
 static struct list_head net_devices = LIST_HEAD_INIT(net_devices);
 static struct mutex probe_disc_mt; /* ch->linked = true, most_nd_open */
-static struct spinlock list_lock;
+static struct spinlock list_lock; /* list_head, ch->linked = false, dev_hold */
 static struct most_aim aim;
 
 static int skb_to_mamac(const struct sk_buff *skb, struct mbo *mbo)
@@ -271,21 +271,29 @@ static void most_nd_setup(struct net_device *dev)
        dev->netdev_ops = &most_nd_ops;
 }
 
-static struct net_dev_context *get_net_dev_context(
-       struct most_interface *iface)
+static struct net_dev_context *get_net_dev(struct most_interface *iface)
+{
+       struct net_dev_context *nd;
+
+       list_for_each_entry(nd, &net_devices, list)
+               if (nd->iface == iface)
+                       return nd;
+       return NULL;
+}
+
+static struct net_dev_context *get_net_dev_hold(struct most_interface *iface)
 {
        struct net_dev_context *nd;
        unsigned long flags;
 
        spin_lock_irqsave(&list_lock, flags);
-       list_for_each_entry(nd, &net_devices, list) {
-               if (nd->iface == iface) {
-                       spin_unlock_irqrestore(&list_lock, flags);
-                       return nd;
-               }
-       }
+       nd = get_net_dev(iface);
+       if (nd && nd->rx.linked && nd->tx.linked)
+               dev_hold(nd->dev);
+       else
+               nd = NULL;
        spin_unlock_irqrestore(&list_lock, flags);
-       return NULL;
+       return nd;
 }
 
 static int aim_probe_channel(struct most_interface *iface, int channel_idx,
@@ -305,7 +313,7 @@ static int aim_probe_channel(struct most_interface *iface, int channel_idx,
                return -EINVAL;
 
        mutex_lock(&probe_disc_mt);
-       nd = get_net_dev_context(iface);
+       nd = get_net_dev(iface);
        if (!nd) {
                dev = alloc_netdev(sizeof(struct net_dev_context), "meth%d",
                                   NET_NAME_UNKNOWN, most_nd_setup);
@@ -354,7 +362,7 @@ static int aim_disconnect_channel(struct most_interface *iface,
        int ret = 0;
 
        mutex_lock(&probe_disc_mt);
-       nd = get_net_dev_context(iface);
+       nd = get_net_dev(iface);
        if (!nd) {
                ret = -EINVAL;
                goto unlock;
@@ -370,12 +378,15 @@ static int aim_disconnect_channel(struct most_interface *iface,
        }
 
        if (nd->rx.linked && nd->tx.linked) {
+               spin_lock_irqsave(&list_lock, flags);
+               ch->linked = false;
+               spin_unlock_irqrestore(&list_lock, flags);
+
                /*
                 * do not call most_stop_channel() here, because channels are
                 * going to be closed in ndo_stop() after unregister_netdev()
                 */
                unregister_netdev(nd->dev);
-               ch->linked = false;
        } else {
                spin_lock_irqsave(&list_lock, flags);
                list_del(&nd->list);
@@ -394,11 +405,17 @@ static int aim_resume_tx_channel(struct most_interface *iface,
 {
        struct net_dev_context *nd;
 
-       nd = get_net_dev_context(iface);
-       if (!nd || nd->tx.ch_id != channel_idx)
+       nd = get_net_dev_hold(iface);
+       if (!nd)
                return 0;
 
+       if (nd->tx.ch_id != channel_idx)
+               goto put_nd;
+
        netif_wake_queue(nd->dev);
+
+put_nd:
+       dev_put(nd->dev);
        return 0;
 }
 
@@ -411,21 +428,31 @@ static int aim_rx_data(struct mbo *mbo)
        struct sk_buff *skb;
        struct net_device *dev;
        unsigned int skb_len;
+       int ret = 0;
 
-       nd = get_net_dev_context(mbo->ifp);
-       if (!nd || nd->rx.ch_id != mbo->hdm_channel_id)
+       nd = get_net_dev_hold(mbo->ifp);
+       if (!nd)
                return -EIO;
 
+       if (nd->rx.ch_id != mbo->hdm_channel_id) {
+               ret = -EIO;
+               goto put_nd;
+       }
+
        dev = nd->dev;
 
        if (nd->is_mamac) {
-               if (!PMS_IS_MAMAC(buf, len))
-                       return -EIO;
+               if (!PMS_IS_MAMAC(buf, len)) {
+                       ret = -EIO;
+                       goto put_nd;
+               }
 
                skb = dev_alloc_skb(len - MDP_HDR_LEN + 2 * ETH_ALEN + 2);
        } else {
-               if (!PMS_IS_MEP(buf, len))
-                       return -EIO;
+               if (!PMS_IS_MEP(buf, len)) {
+                       ret = -EIO;
+                       goto put_nd;
+               }
 
                skb = dev_alloc_skb(len - MEP_HDR_LEN);
        }
@@ -468,7 +495,10 @@ static int aim_rx_data(struct mbo *mbo)
 
 out:
        most_put_mbo(mbo);
-       return 0;
+
+put_nd:
+       dev_put(nd->dev);
+       return ret;
 }
 
 static struct most_aim aim = {
@@ -504,7 +534,7 @@ static void on_netinfo(struct most_interface *iface,
        struct net_device *dev;
        const u8 *m = mac_addr;
 
-       nd = get_net_dev_context(iface);
+       nd = get_net_dev_hold(iface);
        if (!nd)
                return;
 
@@ -526,6 +556,8 @@ static void on_netinfo(struct most_interface *iface,
                                    m[0], m[1], m[2], m[3], m[4], m[5]);
                }
        }
+
+       dev_put(nd->dev);
 }
 
 module_init(most_net_init);