NFC: Reserve tx head and tail room

We can have the NFC core layer allocating the tx head and tail
room for the drivers and avoid 1 or more SKBs copy on write on
the Tx path.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 3 insertions, 14 deletions

diff --git a/drivers/nfc/pn533.c b/drivers/nfc/pn533.c
index c77e0543e502..f81a93e5b59d 100644
--- a/drivers/nfc/pn533.c
+++ b/drivers/nfc/pn533.c
@@ -1246,7 +1246,6 @@ static int pn533_data_exchange_tx_frame(struct pn533 *dev, struct sk_buff *skb)
 {
         int payload_len = skb->len;
         struct pn533_frame *out_frame;
-        struct sk_buff *discarded;
         u8 tg;
 
         nfc_dev_dbg(&dev->interface->dev, "%s - Sending %d bytes", __func__,
@@ -1260,18 +1259,6 @@ static int pn533_data_exchange_tx_frame(struct pn533 *dev, struct sk_buff *skb)
                 return -ENOSYS;
         }
 
-        /* Reserving header space */
-        if (skb_cow_head(skb, PN533_CMD_DATAEXCH_HEAD_LEN)) {
-                nfc_dev_err(&dev->interface->dev, "Error to add header data");
-                return -ENOMEM;
-        }
-
-        /* Reserving tail space, see pn533_tx_frame_finish */
-        if (skb_cow_data(skb, PN533_FRAME_TAIL_SIZE, &discarded) < 0) {
-                nfc_dev_err(&dev->interface->dev, "Error to add tail data");
-                return -ENOMEM;
-        }
-
         skb_push(skb, PN533_CMD_DATAEXCH_HEAD_LEN);
         out_frame = (struct pn533_frame *) skb->data;
 
@@ -1536,7 +1523,9 @@ static int pn533_probe(struct usb_interface *interface,
                         | NFC_PROTO_ISO14443_MASK
                         | NFC_PROTO_NFC_DEP_MASK;
 
-        dev->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols);
+        dev->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols,
+                                           PN533_CMD_DATAEXCH_HEAD_LEN,
+                                           PN533_FRAME_TAIL_SIZE);
         if (!dev->nfc_dev)
                 goto kill_tasklet;