f_phonet: avoid pskb_pull(), fix OOPS with CONFIG_HIGHMEM

This is similar to what we already do in cdc-phonet.c in the same
situation. pskb_pull() refuses to work with HIGHMEM, even if it is
known that the socket buffer is entirely in "low" memory.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 5 deletions

diff --git a/drivers/usb/gadget/f_phonet.c b/drivers/usb/gadget/f_phonet.c
index 3c6e1a058745..5e1495097ec3 100644
--- a/drivers/usb/gadget/f_phonet.c
+++ b/drivers/usb/gadget/f_phonet.c
@@ -346,14 +346,19 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
 
                 if (unlikely(!skb))
                         break;
-                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, 0,
-                                req->actual);
-                page = NULL;
 
-                if (req->actual < req->length) { /* Last fragment */
+                if (skb->len == 0) { /* First fragment */
                         skb->protocol = htons(ETH_P_PHONET);
                         skb_reset_mac_header(skb);
-                        pskb_pull(skb, 1);
+                        /* Can't use pskb_pull() on page in IRQ */
+                        memcpy(skb_put(skb, 1), page_address(page), 1);
+                }
+
+                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
+                                skb->len == 0, req->actual);
+                page = NULL;
+
+                if (req->actual < req->length) { /* Last fragment */
                         skb->dev = dev;
                         dev->stats.rx_packets++;
                         dev->stats.rx_bytes += skb->len;