4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Julian Wiedmann <jwi@xxxxxxxxxxxxxxxxxx>
commit dc5367bcc556e97555fc94a32cd1aadbebdff47e upstream.
With commit e53743994e21
("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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ursula Braun <ubraun@xxxxxxxxxxxxxxxxxx>
Fixes: e53743994e21 ("af_iucv: use paged SKBs for big outbound messages")
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/iucv/af_iucv.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1036,7 +1036,8 @@ static int iucv_sock_sendmsg(struct sock
{
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;
@@ -1114,18 +1115,20 @@ static int iucv_sock_sendmsg(struct sock
* 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);
--
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