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Commit dc5367bc authored by Julian Wiedmann's avatar Julian Wiedmann Committed by David S. Miller
Browse files

net/af_iucv: don't use paged skbs for TX on HiperSockets 



With commit e5374399
("af_iucv: use paged SKBs for big outbound messages"),
we transmit paged skbs for both of AF_IUCV's transport modes
(IUCV or HiperSockets).
The qeth driver for Layer 3 HiperSockets currently doesn't
support NETIF_F_SG, so these skbs would just be linearized again
by the stack.
Avoid that overhead by using paged skbs only for IUCV transport.

cc stable, since this also circumvents a significant skb leak when
sending large messages (where the skb then needs to be linearized).

Signed-off-by: default avatarJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: default avatarUrsula Braun <ubraun@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # v4.8+
Fixes: e5374399 ("af_iucv: use paged SKBs for big outbound messages")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5d722b30

net/iucv/af_iucv.c

+14 −11
Original line number Diff line number Diff line
@@ -1044,7 +1044,8 @@ static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg, 
{

	struct sock *sk = sock->sk;

	struct iucv_sock *iucv = iucv_sk(sk);

	size_t headroom, linear;

	size_t headroom = 0;

	size_t linear;

	struct sk_buff *skb;

	struct iucv_message txmsg = {0};

	struct cmsghdr *cmsg;
@@ -1122,19 +1123,21 @@ static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg, 
	 * this is fine for SOCK_SEQPACKET (unless we want to support

	 * segmented records using the MSG_EOR flag), but

	 * for SOCK_STREAM we might want to improve it in future */

	headroom = (iucv->transport == AF_IUCV_TRANS_HIPER)

		   ? sizeof(struct af_iucv_trans_hdr) + ETH_HLEN : 0;

	if (headroom + len < PAGE_SIZE) {

	if (iucv->transport == AF_IUCV_TRANS_HIPER) {

		headroom = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN;

		linear = len;

	} else {

		if (len < PAGE_SIZE) {

			linear = len;

		} else {

			/* In nonlinear "classic" iucv skb,

			 * reserve space for iucv_array

			 */

		if (iucv->transport != AF_IUCV_TRANS_HIPER)

			headroom += sizeof(struct iucv_array) *

			headroom = sizeof(struct iucv_array) *

				   (MAX_SKB_FRAGS + 1);

			linear = PAGE_SIZE - headroom;

		}

	}

	skb = sock_alloc_send_pskb(sk, headroom + linear, len - linear,

				   noblock, &err, 0);

	if (!skb)