Subject: Re: WARNING: at net/ipv4/tcp.c:1610 tcp_recvmsg+0xb1b/0xc70()

From: Jack Stone <[email-masked]>
Date: Mon, 28 May 2012 09:34:05 +0100

On 05/28/2012 01:25 AM, Eric Dumazet wrote:
> On Sun, 2012-05-27 at 20:13 +0100, Jack Stone wrote:
> 
>> Could it be something to do with my staging network driver?
> 
> drivers/staging/rtl8712/rtl8712_recv.c
> 
> line 1096
> 
> precvframe->u.hdr.pkt = skb_clone(pskb, GFP_ATOMIC);
> 
> This looks very wrong.
> Make sure you never _never_ hit this path.
> 

I've applied the following debugging patch. Thanks for the suggestion.

diff --git a/drivers/staging/rtl8712/rtl8712_recv.c b/drivers/staging/rtl8712/rtl8712_recv.c
index 8e82ce2..fed62f8 100644
--- a/drivers/staging/rtl8712/rtl8712_recv.c
+++ b/drivers/staging/rtl8712/rtl8712_recv.c
@@ -1082,23 +1082,16 @@ static int recvbuf2recvframe(struct _adapter *padapter, struct sk_buff *pskb)
                 * 4 is for skb->data 4 bytes alignment. */
                alloc_sz += 6;
                pkt_copy = netdev_alloc_skb(padapter->pnetdev, alloc_sz);
-               if (pkt_copy) {
-                       pkt_copy->dev = padapter->pnetdev;
-                       precvframe->u.hdr.pkt = pkt_copy;
-                       skb_reserve(pkt_copy, 4 - ((addr_t)(pkt_copy->data)
-                                   % 4));
-                       skb_reserve(pkt_copy, shift_sz);
-                       memcpy(pkt_copy->data, pbuf, tmp_len);
-                       precvframe->u.hdr.rx_head = precvframe->u.hdr.rx_data =
-                                precvframe->u.hdr.rx_tail = pkt_copy->data;
-                       precvframe->u.hdr.rx_end = pkt_copy->data + alloc_sz;
-               } else {
-                       precvframe->u.hdr.pkt = skb_clone(pskb, GFP_ATOMIC);
-                       precvframe->u.hdr.rx_head = pbuf;
-                       precvframe->u.hdr.rx_data = pbuf;
-                       precvframe->u.hdr.rx_tail = pbuf;
-                       precvframe->u.hdr.rx_end = pbuf + alloc_sz;
-               }
+               WARN_ON(!pkt_copy)
+               pkt_copy->dev = padapter->pnetdev;
+               precvframe->u.hdr.pkt = pkt_copy;
+               skb_reserve(pkt_copy, 4 - ((addr_t)(pkt_copy->data)
+                           % 4));
+               skb_reserve(pkt_copy, shift_sz);
+               memcpy(pkt_copy->data, pbuf, tmp_len);
+               precvframe->u.hdr.rx_head = precvframe->u.hdr.rx_data =
+                        precvframe->u.hdr.rx_tail = pkt_copy->data;
+               precvframe->u.hdr.rx_end = pkt_copy->data + alloc_sz;
                recvframe_put(precvframe, tmp_len);
                recvframe_pull(precvframe, drvinfo_sz + RXDESC_SIZE);
                /* because the endian issue, driver avoid reference to the