Messages in this thread | | | Date | Fri, 24 May 2002 10:04:34 +0200 | From | Wolfgang Wegner <> | Subject | sk_buff misunderstanding? |
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Hi all,
i am trying to do some modification in the kernel to get some different timestamp directly from a modified network driver, and am having some difficulty (or maybe misunderstanding) with sk_buff's...
- struct sk_buff has a new member, struct ww_timestamp rcvtime, containing the actual timestamp and a flag is_valid - the driver (currently orinoco.c from pcmcia_cs) is modified to fill the my_timestamp struct and sets is_valid. - when passing the packet to a socket, this new timestamp is evaluated (in sock_recv_timestamp, where both sk_buff _and_ sock are known)
The problem is: in sock_recv_timestamp, is_valid is reset to 0 - and i have no idea why.
Here are the last relevant lines in orinoco.c: (orinoco_ev_rx) /* WW_TIMESTAMP stuff */ skb->rcvtime=rcvtime; printk("orinoco.c: skb=%p\n",skb);
skb->rcvtime.is_valid=1; /* Pass the packet to the networking stack */ netif_rx(skb);
Here is include/net/sock.h (tsbucket is an extension i made) static __inline__ void sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb) { if (sk->rcvtstamp) put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP, sizeof(skb->stamp), &skb ->stamp); else sk->stamp = skb->stamp; if((sk->tsbucket)) printk("skb=%p, timestamp.is_valid=%d!\n",skb,skb->rcvtime.is_valid);
My first idea was that maybe the skb is copied around before, so i put some printk in skb_head_from_pool - but this seems not to be the case. Here is what the kernel says: (no lines left out!)
May 24 08:55:43 licht kernel: skb_head_from_pool, skb=cfaa6d80 May 24 08:55:43 licht kernel: orinoco.c: skb=cfaa6d80 May 24 08:55:43 licht kernel: skb=cfaa6d80, timestamp.is_valid=0! May 24 08:55:43 licht kernel: skb_head_from_pool, skb=cfaa6d80 May 24 08:55:43 licht kernel: skb_head_from_pool, skb=cf0fa200
I am out of ideas - anybody else? (This must be some really stupid bug or misunderstanding of mine, i guess, but i really have no idea what i overlooked.)
Any help is appreciated.
Thanks, Wolfgang
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