NFC: Fixed nfc core and hci unregistration and cleanup

When an adapter is removed, it will unregister itself from hci and/or
nfc core. In order to do that safely, work tasks must first be canceled
and prevented to be scheduled again, before the hci or nfc device can be
destroyed.

Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 22 insertions, 25 deletions

diff --git a/net/nfc/core.c b/net/nfc/core.c
index aa64ea441676..7d7b4ee34015 100644
--- a/net/nfc/core.c
+++ b/net/nfc/core.c
@@ -338,7 +338,7 @@ int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol)
                 dev->active_target = target;
                 dev->rf_mode = NFC_RF_INITIATOR;
 
-                if (dev->ops->check_presence)
+                if (dev->ops->check_presence && !dev->shutting_down)
                         mod_timer(&dev->check_pres_timer, jiffies +
                                   msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
         }
@@ -429,7 +429,7 @@ int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
                 rc = dev->ops->im_transceive(dev, dev->active_target, skb, cb,
                                              cb_context);
 
-                if (!rc && dev->ops->check_presence)
+                if (!rc && dev->ops->check_presence && !dev->shutting_down)
                         mod_timer(&dev->check_pres_timer, jiffies +
                                   msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
         } else if (dev->rf_mode == NFC_RF_TARGET && dev->ops->tm_send != NULL) {
@@ -684,11 +684,6 @@ static void nfc_release(struct device *d)
 
         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 
-        if (dev->ops->check_presence) {
-                del_timer_sync(&dev->check_pres_timer);
-                cancel_work_sync(&dev->check_pres_work);
-        }
-
         nfc_genl_data_exit(&dev->genl_data);
         kfree(dev->targets);
         kfree(dev);
@@ -706,15 +701,16 @@ static void nfc_check_pres_work(struct work_struct *work)
                 rc = dev->ops->check_presence(dev, dev->active_target);
                 if (rc == -EOPNOTSUPP)
                         goto exit;
-                if (!rc) {
-                        mod_timer(&dev->check_pres_timer, jiffies +
-                                  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
-                } else {
+                if (rc) {
                         u32 active_target_idx = dev->active_target->idx;
                         device_unlock(&dev->dev);
                         nfc_target_lost(dev, active_target_idx);
                         return;
                 }
+
+                if (!dev->shutting_down)
+                        mod_timer(&dev->check_pres_timer, jiffies +
+                                  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
         }
 
 exit:
@@ -853,26 +849,27 @@ void nfc_unregister_device(struct nfc_dev *dev)
 
         id = dev->idx;
 
-        mutex_lock(&nfc_devlist_mutex);
-        nfc_devlist_generation++;
-
-        /* lock to avoid unregistering a device while an operation
-           is in progress */
-        device_lock(&dev->dev);
-        device_del(&dev->dev);
-        device_unlock(&dev->dev);
+        if (dev->ops->check_presence) {
+                device_lock(&dev->dev);
+                dev->shutting_down = true;
+                device_unlock(&dev->dev);
+                del_timer_sync(&dev->check_pres_timer);
+                cancel_work_sync(&dev->check_pres_work);
+        }
 
-        mutex_unlock(&nfc_devlist_mutex);
+        rc = nfc_genl_device_removed(dev);
+        if (rc)
+                pr_debug("The userspace won't be notified that the device %s "
+                         "was removed\n", dev_name(&dev->dev));
 
         nfc_llcp_unregister_device(dev);
 
-        rc = nfc_genl_device_removed(dev);
-        if (rc)
-                pr_debug("The userspace won't be notified that the device %s was removed\n",
-                         dev_name(&dev->dev));
+        mutex_lock(&nfc_devlist_mutex);
+        nfc_devlist_generation++;
+        device_del(&dev->dev);
+        mutex_unlock(&nfc_devlist_mutex);
 
         ida_simple_remove(&nfc_index_ida, id);
-
 }
 EXPORT_SYMBOL(nfc_unregister_device);