[PATCH net 0/3] net/af_iucv: fixes 2019-06-18

[PATCH net 0/3] net/af_iucv: fixes 2019-06-18

[Julian Wiedmann]

Hi Dave,
I spent a few cycles on transmit problems for af_iucv over regular
netdevices - please apply the following fixes to -net.

The first patch allows for skb allocations outside of GFP_DMA, while the
second patch respects that drivers might use skb_cow_head() and/or want
additional dev->needed_headroom.
Patch 3 is for a separate issue, where we didn't setup some of the
netdevice-specific infrastructure when running as a z/VM guest.

Thanks,
Julian


Julian Wiedmann (3):
  net/af_iucv: remove GFP_DMA restriction for HiperTransport
  net/af_iucv: build proper skbs for HiperTransport
  net/af_iucv: always register net_device notifier

 net/iucv/af_iucv.c | 49 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 36 insertions(+), 13 deletions(-)

-- 
2.17.1

[PATCH net 1/3] net/af_iucv: remove GFP_DMA restriction for HiperTransport

[Julian Wiedmann]

af_iucv sockets over z/VM IUCV require that their skbs are allocated
in DMA memory. This restriction doesn't apply to connections over
HiperSockets. So only set this limit for z/VM IUCV sockets, thereby
increasing the likelihood that the large (and linear!) allocations for
HiperTransport messages succeed.

Fixes: 3881ac441f64 ("af_iucv: add HiperSockets transport")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
---
 net/iucv/af_iucv.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 36eb8d1d9128..2ee68d2d4693 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -588,7 +588,6 @@ static struct sock *iucv_sock_alloc(struct socket *sock, int proto, gfp_t prio,
 
 	sk->sk_destruct = iucv_sock_destruct;
 	sk->sk_sndtimeo = IUCV_CONN_TIMEOUT;
-	sk->sk_allocation = GFP_DMA;
 
 	sock_reset_flag(sk, SOCK_ZAPPED);
 
@@ -782,6 +781,7 @@ static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
 		memcpy(iucv->src_user_id, iucv_userid, 8);
 		sk->sk_state = IUCV_BOUND;
 		iucv->transport = AF_IUCV_TRANS_IUCV;
+		sk->sk_allocation |= GFP_DMA;
 		if (!iucv->msglimit)
 			iucv->msglimit = IUCV_QUEUELEN_DEFAULT;
 		goto done_unlock;
@@ -806,6 +806,8 @@ static int iucv_sock_autobind(struct sock *sk)
 		return -EPROTO;
 
 	memcpy(iucv->src_user_id, iucv_userid, 8);
+	iucv->transport = AF_IUCV_TRANS_IUCV;
+	sk->sk_allocation |= GFP_DMA;
 
 	write_lock_bh(&iucv_sk_list.lock);
 	__iucv_auto_name(iucv);
@@ -1781,6 +1783,8 @@ static int iucv_callback_connreq(struct iucv_path *path,
 
 	niucv = iucv_sk(nsk);
 	iucv_sock_init(nsk, sk);
+	niucv->transport = AF_IUCV_TRANS_IUCV;
+	nsk->sk_allocation |= GFP_DMA;
 
 	/* Set the new iucv_sock */
 	memcpy(niucv->dst_name, ipuser + 8, 8);
-- 
2.17.1

[PATCH net 2/3] net/af_iucv: build proper skbs for HiperTransport

[Julian Wiedmann]

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>
---
 net/iucv/af_iucv.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 2ee68d2d4693..5264a182d2c3 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -14,6 +14,7 @@
 #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>
@@ -347,14 +348,14 @@ static int afiucv_hs_send(struct iucv_message *imsg, struct sock *sock,
 	if (imsg)
 		memcpy(&phs_hdr->iucv_hdr, imsg, sizeof(struct iucv_message));
 
-	skb_push(skb, ETH_HLEN);
-	memset(skb->data, 0, ETH_HLEN);
-
 	skb->dev = iucv->hs_dev;
 	if (!skb->dev) {
 		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 +368,8 @@ 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 +469,14 @@ 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;
@@ -1133,7 +1138,8 @@ 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) {
-- 
2.17.1

[PATCH net 3/3] net/af_iucv: always register net_device notifier

[Julian Wiedmann]

Even when running as VM guest (ie pr_iucv != NULL), af_iucv can still
open HiperTransport-based connections. For robust operation these
connections require the af_iucv_netdev_notifier, so register it
unconditionally.

Also handle any error that register_netdevice_notifier() returns.

Fixes: 9fbd87d41392 ("af_iucv: handle netdev events")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
---
 net/iucv/af_iucv.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 5264a182d2c3..09e1694b6d34 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -2440,6 +2440,13 @@ static int afiucv_iucv_init(void)
 	return err;
 }
 
+static void afiucv_iucv_exit(void)
+{
+	device_unregister(af_iucv_dev);
+	driver_unregister(&af_iucv_driver);
+	pr_iucv->iucv_unregister(&af_iucv_handler, 0);
+}
+
 static int __init afiucv_init(void)
 {
 	int err;
@@ -2473,11 +2480,18 @@ static int __init afiucv_init(void)
 		err = afiucv_iucv_init();
 		if (err)
 			goto out_sock;
-	} else
-		register_netdevice_notifier(&afiucv_netdev_notifier);
+	}
+
+	err = register_netdevice_notifier(&afiucv_netdev_notifier);
+	if (err)
+		goto out_notifier;
+
 	dev_add_pack(&iucv_packet_type);
 	return 0;
 
+out_notifier:
+	if (pr_iucv)
+		afiucv_iucv_exit();
 out_sock:
 	sock_unregister(PF_IUCV);
 out_proto:
@@ -2491,12 +2505,11 @@ static int __init afiucv_init(void)
 static void __exit afiucv_exit(void)
 {
 	if (pr_iucv) {
-		device_unregister(af_iucv_dev);
-		driver_unregister(&af_iucv_driver);
-		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
+		afiucv_iucv_exit();
 		symbol_put(iucv_if);
-	} else
-		unregister_netdevice_notifier(&afiucv_netdev_notifier);
+	}
+
+	unregister_netdevice_notifier(&afiucv_netdev_notifier);
 	dev_remove_pack(&iucv_packet_type);
 	sock_unregister(PF_IUCV);
 	proto_unregister(&iucv_proto);
-- 
2.17.1

Re: [PATCH net 0/3] net/af_iucv: fixes 2019-06-18

[David Miller]

From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Tue, 18 Jun 2019 20:42:58 +0200

> I spent a few cycles on transmit problems for af_iucv over regular
> netdevices - please apply the following fixes to -net.
> 
> The first patch allows for skb allocations outside of GFP_DMA, while the
> second patch respects that drivers might use skb_cow_head() and/or want
> additional dev->needed_headroom.
> Patch 3 is for a separate issue, where we didn't setup some of the
> netdevice-specific infrastructure when running as a z/VM guest.

Series applied.