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Subject[PATCH 4.19 437/639] net/af_iucv: build proper skbs for HiperTransport
Date
From: Julian Wiedmann <jwi@linux.ibm.com>

[ Upstream commit 238965b71b968dc5b3c0fe430e946f488322c4b5 ]

The HiperSockets-based transport path in af_iucv is still too closely
entangled with qeth.
With commit a647a02512ca ("s390/qeth: speed-up L3 IQD xmit"), the
relevant xmit code in qeth has begun to use skb_cow_head(). So to avoid
unnecessary skb head expansions, af_iucv must learn to
1) respect dev->needed_headroom when allocating skbs, and
2) drop the header reference before cloning the skb.

While at it, also stop hard-coding the LL-header creation stage and just
use the appropriate helper.

Fixes: a647a02512ca ("s390/qeth: speed-up L3 IQD xmit")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/iucv/af_iucv.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index f024914da1b2d..e07daee1227c3 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -13,6 +13,7 @@
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
+#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
@@ -355,6 +356,9 @@ static int afiucv_hs_send(struct iucv_message *imsg, struct sock *sock,
err = -ENODEV;
goto err_free;
}
+
+ dev_hard_header(skb, skb->dev, ETH_P_AF_IUCV, NULL, NULL, skb->len);
+
if (!(skb->dev->flags & IFF_UP) || !netif_carrier_ok(skb->dev)) {
err = -ENETDOWN;
goto err_free;
@@ -367,6 +371,8 @@ static int afiucv_hs_send(struct iucv_message *imsg, struct sock *sock,
skb_trim(skb, skb->dev->mtu);
}
skb->protocol = cpu_to_be16(ETH_P_AF_IUCV);
+
+ __skb_header_release(skb);
nskb = skb_clone(skb, GFP_ATOMIC);
if (!nskb) {
err = -ENOMEM;
@@ -466,12 +472,14 @@ static void iucv_sever_path(struct sock *sk, int with_user_data)
/* Send controlling flags through an IUCV socket for HIPER transport */
static int iucv_send_ctrl(struct sock *sk, u8 flags)
{
+ struct iucv_sock *iucv = iucv_sk(sk);
int err = 0;
int blen;
struct sk_buff *skb;
u8 shutdown = 0;

- blen = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN;
+ blen = sizeof(struct af_iucv_trans_hdr) +
+ LL_RESERVED_SPACE(iucv->hs_dev);
if (sk->sk_shutdown & SEND_SHUTDOWN) {
/* controlling flags should be sent anyway */
shutdown = sk->sk_shutdown;
@@ -1131,7 +1139,8 @@ static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg,
* segmented records using the MSG_EOR flag), but
* for SOCK_STREAM we might want to improve it in future */
if (iucv->transport == AF_IUCV_TRANS_HIPER) {
- headroom = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN;
+ headroom = sizeof(struct af_iucv_trans_hdr) +
+ LL_RESERVED_SPACE(iucv->hs_dev);
linear = len;
} else {
if (len < PAGE_SIZE) {
--
2.20.1


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