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

With commit e53743994e
("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: e53743994e ("af_iucv: use paged SKBs for big outbound messages")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Julian Wiedmann 2017-01-10 17:10:34 +01:00 committed by David S. Miller
parent 5d722b3024
commit dc5367bcc5
1 changed files with 14 additions and 11 deletions
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25
net/iucv/af_iucv.c
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@ -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;
@ -1122,18 +1123,20 @@ 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 {
/* In nonlinear "classic" iucv skb,
* reserve space for iucv_array
*/
if (iucv->transport != AF_IUCV_TRANS_HIPER)
headroom += sizeof(struct iucv_array) *
(MAX_SKB_FRAGS + 1);
linear = PAGE_SIZE - headroom;
if (len < PAGE_SIZE) {
linear = len;
} else {
/* In nonlinear "classic" iucv skb,
* reserve space for 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);