NFC: Do not return EBUSY when stopping a poll that's already stopped

We check for the polling flag before checking if the netlink PID caller
match.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index 03c31db38f12..99bc6f7faa7b 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -634,6 +634,15 @@ static int nfc_genl_stop_poll(struct sk_buff *skb, struct genl_info *info)
         if (!dev)
                 return -ENODEV;
 
+        device_lock(&dev->dev);
+
+        if (!dev->polling) {
+                device_unlock(&dev->dev);
+                return -EINVAL;
+        }
+
+        device_unlock(&dev->dev);
+
         mutex_lock(&dev->genl_data.genl_data_mutex);
 
         if (dev->genl_data.poll_req_pid != info->snd_pid) {