[PATCH 2/4] tun: Use iovec iterators

From: Herbert Xu
Date: Fri Nov 07 2014 - 08:24:07 EST


This patch removes the use of skb_copy_datagram_const_iovec in
favour of the iovec iterator-based skb_copy_datagram_iter.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
---

drivers/net/tun.c | 65 ++++++++++++++++++++++++------------------------------
1 file changed, 30 insertions(+), 35 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9dd3746..2ff769b 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -71,6 +71,7 @@
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <linux/seq_file.h>
+#include <linux/uio.h>

#include <asm/uaccess.h>

@@ -1230,11 +1231,11 @@ static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
static ssize_t tun_put_user(struct tun_struct *tun,
struct tun_file *tfile,
struct sk_buff *skb,
- const struct iovec *iv, int len)
+ struct iov_iter *iter)
{
struct tun_pi pi = { 0, skb->protocol };
- ssize_t total = 0;
- int vlan_offset = 0, copied;
+ ssize_t total;
+ int vlan_offset;
int vlan_hlen = 0;
int vnet_hdr_sz = 0;

@@ -1244,23 +1245,25 @@ static ssize_t tun_put_user(struct tun_struct *tun,
if (tun->flags & TUN_VNET_HDR)
vnet_hdr_sz = tun->vnet_hdr_sz;

+ total = skb->len + vlan_hlen + vnet_hdr_sz;
+
if (!(tun->flags & TUN_NO_PI)) {
- if ((len -= sizeof(pi)) < 0)
+ if (iov_iter_count(iter) < sizeof(pi))
return -EINVAL;

- if (len < skb->len + vlan_hlen + vnet_hdr_sz) {
+ total += sizeof(pi);
+ if (iov_iter_count(iter) < total) {
/* Packet will be striped */
pi.flags |= TUN_PKT_STRIP;
}

- if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
+ if (copy_to_iter(&pi, sizeof(pi), iter) != sizeof(pi))
return -EFAULT;
- total += sizeof(pi);
}

if (vnet_hdr_sz) {
struct virtio_net_hdr gso = { 0 }; /* no info leak */
- if ((len -= vnet_hdr_sz) < 0)
+ if (iov_iter_count(iter) < vnet_hdr_sz)
return -EINVAL;

if (skb_is_gso(skb)) {
@@ -1299,17 +1302,12 @@ static ssize_t tun_put_user(struct tun_struct *tun,
gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
} /* else everything is zero */

- if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
- sizeof(gso))))
+ if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
return -EFAULT;
- total += vnet_hdr_sz;
}

- copied = total;
- len = min_t(int, skb->len + vlan_hlen, len);
- total += skb->len + vlan_hlen;
if (vlan_hlen) {
- int copy, ret;
+ int ret;
struct {
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
@@ -1320,36 +1318,32 @@ static ssize_t tun_put_user(struct tun_struct *tun,

vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);

- copy = min_t(int, vlan_offset, len);
- ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
- len -= copy;
- copied += copy;
- if (ret || !len)
+ ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
+ if (ret || !iov_iter_count(iter))
goto done;

- copy = min_t(int, sizeof(veth), len);
- ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
- len -= copy;
- copied += copy;
- if (ret || !len)
+ ret = copy_to_iter(&veth, sizeof(veth), iter);
+ if (ret != sizeof(veth) || !iov_iter_count(iter))
goto done;
}

- skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
+ skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);

done:
tun->dev->stats.tx_packets++;
- tun->dev->stats.tx_bytes += len;
+ tun->dev->stats.tx_bytes += skb->len + vlan_hlen;

return total;
}

static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
- const struct iovec *iv, ssize_t len, int noblock)
+ const struct iovec *iv, unsigned long segs,
+ ssize_t len, int noblock)
{
struct sk_buff *skb;
ssize_t ret = 0;
int peeked, err, off = 0;
+ struct iov_iter iter;

tun_debug(KERN_INFO, tun, "tun_do_read\n");

@@ -1362,11 +1356,12 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
/* Read frames from queue */
skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
&peeked, &off, &err);
- if (skb) {
- ret = tun_put_user(tun, tfile, skb, iv, len);
- kfree_skb(skb);
- } else
- ret = err;
+ if (!skb)
+ return ret;
+
+ iov_iter_init(&iter, READ, iv, segs, len);
+ ret = tun_put_user(tun, tfile, skb, &iter);
+ kfree_skb(skb);

return ret;
}
@@ -1387,7 +1382,7 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
goto out;
}

- ret = tun_do_read(tun, tfile, iv, len,
+ ret = tun_do_read(tun, tfile, iv, count, len,
file->f_flags & O_NONBLOCK);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
@@ -1488,7 +1483,7 @@ static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
SOL_PACKET, TUN_TX_TIMESTAMP);
goto out;
}
- ret = tun_do_read(tun, tfile, m->msg_iov, total_len,
+ ret = tun_do_read(tun, tfile, m->msg_iov, m->msg_iovlen, total_len,
flags & MSG_DONTWAIT);
if (ret > total_len) {
m->msg_flags |= MSG_TRUNC;
--
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