net/af_iucv: don't use paged skbs for TX on HiperSockets (dc5367bc) · Commits · 戴 / test

With commit ("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:

Julian Wiedmann <jwi@linux.vnet.ibm.com> Signed-off-by:

Ursula Braun <ubraun@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> # v4.8+ Fixes: ("af_iucv: use paged SKBs for big outbound messages") Signed-off-by:

David S. Miller <davem@davemloft.net>

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)

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