Hi Mat, * Gustavo F. Padovan <[email protected]> [2010-08-11 00:35:41 -0300]:
> * Mat Martineau <[email protected]> [2010-08-10 12:15:00 -0700]: > > > In order to not limit ERTM and streaming mode PDUs to the HCI MTU > > size, L2CAP must be able to split PDUs in to multple HCI fragments. > > This is done by allocating space for the FCS in the last fragment. > > > > Signed-off-by: Mat Martineau <[email protected]> > > --- > > net/bluetooth/l2cap.c | 39 ++++++++++++++++++++++++++++++++++----- > > 1 files changed, 34 insertions(+), 5 deletions(-) > > > > diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c > > index aa69c84..b485c4a 100644 > > --- a/net/bluetooth/l2cap.c > > +++ b/net/bluetooth/l2cap.c > > @@ -1664,31 +1664,63 @@ static inline int l2cap_skbuff_fromiovec(struct > > sock *sk, struct msghdr *msg, in > > { > > struct l2cap_conn *conn = l2cap_pi(sk)->conn; > > struct sk_buff **frag; > > + struct sk_buff *final; > > int err, sent = 0; > > > > + BT_DBG("sk %p, msg %p, len %d, count %d, skb %p", sk, > > + msg, (int)len, (int)count, skb); > > + > > if (memcpy_fromiovec(skb_put(skb, count), msg->msg_iov, count)) > > return -EFAULT; > > > > sent += count; > > len -= count; > > + final = skb; > > > > /* Continuation fragments (no L2CAP header) */ > > frag = &skb_shinfo(skb)->frag_list; > > while (len) { > > + int skblen; > > count = min_t(unsigned int, conn->mtu, len); > > > > - *frag = bt_skb_send_alloc(sk, count, msg->msg_flags & > > MSG_DONTWAIT, &err); > > + /* Add room for the FCS if it fits */ > > + if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16 && > > + len + L2CAP_FCS_SIZE <= conn->mtu) > > You don't need to check for (len + L2CAP_FCS_SIZE <= conn=mtu) here. > Section 5.1 point that: > > "Unlike the B-Frame length field, the I-frame length field may be greater > than the configured MTU because it includes the octet lengths of the > Control, L2CAP SDU Length (when present), and frame check sequence > fields as well as the Information octets." > > From that I understand "len <=" and not "len + L2CAP_FCS_SIZE <=" So here you might want to the check if we support FCS, and then add 2 to skblen. > > > > + skblen = count + L2CAP_FCS_SIZE; > > + else > > + skblen = count; > > + > > + *frag = bt_skb_send_alloc(sk, skblen, > > + msg->msg_flags & MSG_DONTWAIT, &err); > > if (!*frag) > > return -EFAULT; > > - if (memcpy_fromiovec(skb_put(*frag, count), msg->msg_iov, > > count)) > > + > > + if (memcpy_fromiovec(skb_put(*frag, count), > > + msg->msg_iov, count)) > > return -EFAULT; > > > > sent += count; > > len -= count; > > > > + final = *frag; > > + > > frag = &(*frag)->next; > > } > > > > + if (l2cap_pi(sk)->fcs == L2CAP_FCS_CRC16) { > > + if (skb_tailroom(final) < L2CAP_FCS_SIZE) { > > + *frag = bt_skb_send_alloc(sk, L2CAP_FCS_SIZE, > > + msg->msg_flags & MSG_DONTWAIT, > > + &err); Why do we need to check for FCS again? We already added it required space to the last fragment. -- Gustavo F. Padovan http://padovan.org -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
