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Message-Id: <1389682387-28601-1-git-send-email-jasowang@redhat.com>
Date: Tue, 14 Jan 2014 14:53:07 +0800
From: Jason Wang <jasowang@...hat.com>
To: davem@...emloft.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Jason Wang <jasowang@...hat.com>,
Vlad Yasevich <vyasevic@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
John Fastabend <john.r.fastabend@...el.com>,
Stephen Hemminger <stephen@...workplumber.org>,
Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH net-next] tun/macvtap: limit the packets queued through rcvbuf
We used to limit the number of packets queued through tx_queue_length. This
has several issues:
- tx_queue_length is the control of qdisc queue length, simply reusing it
to control the packets queued by device may cause confusion.
- After commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523 ("macvtap: Add
support of packet capture on macvtap device."), an unexpected qdisc
caused by non-zero tx_queue_length will lead qdisc lock contention for
multiqueue deivce.
- What we really want is to limit the total amount of memory occupied not
the number of packets.
So this patch tries to solve the above issues by using socket rcvbuf to
limit the packets could be queued for tun/macvtap. This was done by using
sock_queue_rcv_skb() instead of a direct call to skb_queue_tail(). Also two
new ioctl() were introduced for userspace to change the rcvbuf like what we
have done for sndbuf.
With this fix, we can safely change the tx_queue_len of macvtap to
zero. This will make multiqueue works without extra lock contention.
Cc: Vlad Yasevich <vyasevic@...hat.com>
Cc: Michael S. Tsirkin <mst@...hat.com>
Cc: John Fastabend <john.r.fastabend@...el.com>
Cc: Stephen Hemminger <stephen@...workplumber.org>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
drivers/net/macvtap.c | 31 ++++++++++++++++++++---------
drivers/net/tun.c | 48 +++++++++++++++++++++++++++++++++------------
include/uapi/linux/if_tun.h | 3 +++
3 files changed, 60 insertions(+), 22 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a2c3a89..c429c56 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -292,9 +292,6 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb)
if (!q)
return RX_HANDLER_PASS;
- if (skb_queue_len(&q->sk.sk_receive_queue) >= dev->tx_queue_len)
- goto drop;
-
skb_push(skb, ETH_HLEN);
/* Apply the forward feature mask so that we perform segmentation
@@ -310,8 +307,10 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb)
goto drop;
if (!segs) {
- skb_queue_tail(&q->sk.sk_receive_queue, skb);
- goto wake_up;
+ if (sock_queue_rcv_skb(&q->sk, skb))
+ goto drop;
+ else
+ goto wake_up;
}
kfree_skb(skb);
@@ -319,11 +318,17 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb)
struct sk_buff *nskb = segs->next;
segs->next = NULL;
- skb_queue_tail(&q->sk.sk_receive_queue, segs);
+ if (sock_queue_rcv_skb(&q->sk, segs)) {
+ skb = segs;
+ skb->next = nskb;
+ goto drop;
+ }
+
segs = nskb;
}
} else {
- skb_queue_tail(&q->sk.sk_receive_queue, skb);
+ if (sock_queue_rcv_skb(&q->sk, skb))
+ goto drop;
}
wake_up:
@@ -333,7 +338,7 @@ wake_up:
drop:
/* Count errors/drops only here, thus don't care about args. */
macvlan_count_rx(vlan, 0, 0, 0);
- kfree_skb(skb);
+ kfree_skb_list(skb);
return RX_HANDLER_CONSUMED;
}
@@ -414,7 +419,7 @@ static void macvtap_dellink(struct net_device *dev,
static void macvtap_setup(struct net_device *dev)
{
macvlan_common_setup(dev);
- dev->tx_queue_len = TUN_READQ_SIZE;
+ dev->tx_queue_len = 0;
}
static struct rtnl_link_ops macvtap_link_ops __read_mostly = {
@@ -469,6 +474,7 @@ static int macvtap_open(struct inode *inode, struct file *file)
sock_init_data(&q->sock, &q->sk);
q->sk.sk_write_space = macvtap_sock_write_space;
q->sk.sk_destruct = macvtap_sock_destruct;
+ q->sk.sk_rcvbuf = TUN_RCVBUF;
q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
@@ -1040,6 +1046,13 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
q->sk.sk_sndbuf = u;
return 0;
+ case TUNSETRCVBUF:
+ if (get_user(u, up))
+ return -EFAULT;
+
+ q->sk.sk_rcvbuf = u;
+ return 0;
+
case TUNGETVNETHDRSZ:
s = q->vnet_hdr_sz;
if (put_user(s, sp))
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 09f6662..7a08fa3 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -177,6 +177,7 @@ struct tun_struct {
int vnet_hdr_sz;
int sndbuf;
+ int rcvbuf;
struct tap_filter txflt;
struct sock_fprog fprog;
/* protected by rtnl lock */
@@ -771,17 +772,6 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
if (!check_filter(&tun->txflt, skb))
goto drop;
- if (tfile->socket.sk->sk_filter &&
- sk_filter(tfile->socket.sk, skb))
- goto drop;
-
- /* Limit the number of packets queued by dividing txq length with the
- * number of queues.
- */
- if (skb_queue_len(&tfile->socket.sk->sk_receive_queue)
- >= dev->tx_queue_len / tun->numqueues)
- goto drop;
-
if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
goto drop;
@@ -798,7 +788,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
nf_reset(skb);
/* Enqueue packet */
- skb_queue_tail(&tfile->socket.sk->sk_receive_queue, skb);
+ if (sock_queue_rcv_skb(tfile->socket.sk, skb))
+ goto drop;
/* Notify and wake up reader process */
if (tfile->flags & TUN_FASYNC)
@@ -1668,6 +1659,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun->filter_attached = false;
tun->sndbuf = tfile->socket.sk->sk_sndbuf;
+ tun->rcvbuf = tfile->socket.sk->sk_rcvbuf;
spin_lock_init(&tun->lock);
@@ -1837,6 +1829,17 @@ static void tun_set_sndbuf(struct tun_struct *tun)
}
}
+static void tun_set_rcvbuf(struct tun_struct *tun)
+{
+ struct tun_file *tfile;
+ int i;
+
+ for (i = 0; i < tun->numqueues; i++) {
+ tfile = rtnl_dereference(tun->tfiles[i]);
+ tfile->socket.sk->sk_sndbuf = tun->sndbuf;
+ }
+}
+
static int tun_set_queue(struct file *file, struct ifreq *ifr)
{
struct tun_file *tfile = file->private_data;
@@ -1878,7 +1881,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
struct ifreq ifr;
kuid_t owner;
kgid_t group;
- int sndbuf;
+ int sndbuf, rcvbuf;
int vnet_hdr_sz;
unsigned int ifindex;
int ret;
@@ -2061,6 +2064,22 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
tun_set_sndbuf(tun);
break;
+ case TUNGETRCVBUF:
+ rcvbuf = tfile->socket.sk->sk_rcvbuf;
+ if (copy_to_user(argp, &rcvbuf, sizeof(rcvbuf)))
+ ret = -EFAULT;
+ break;
+
+ case TUNSETRCVBUF:
+ if (copy_from_user(&rcvbuf, argp, sizeof(rcvbuf))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ tun->rcvbuf = rcvbuf;
+ tun_set_rcvbuf(tun);
+ break;
+
case TUNGETVNETHDRSZ:
vnet_hdr_sz = tun->vnet_hdr_sz;
if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
@@ -2139,6 +2158,8 @@ static long tun_chr_compat_ioctl(struct file *file,
case TUNSETTXFILTER:
case TUNGETSNDBUF:
case TUNSETSNDBUF:
+ case TUNGETRCVBUF:
+ case TUNSETRCVBUF:
case SIOCGIFHWADDR:
case SIOCSIFHWADDR:
arg = (unsigned long)compat_ptr(arg);
@@ -2204,6 +2225,7 @@ static int tun_chr_open(struct inode *inode, struct file * file)
tfile->sk.sk_write_space = tun_sock_write_space;
tfile->sk.sk_sndbuf = INT_MAX;
+ tfile->sk.sk_rcvbuf = TUN_RCVBUF;
file->private_data = tfile;
set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index e9502dd..8e04657 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -22,6 +22,7 @@
/* Read queue size */
#define TUN_READQ_SIZE 500
+#define TUN_RCVBUF (512 * PAGE_SIZE)
/* TUN device flags */
#define TUN_TUN_DEV 0x0001
@@ -58,6 +59,8 @@
#define TUNSETQUEUE _IOW('T', 217, int)
#define TUNSETIFINDEX _IOW('T', 218, unsigned int)
#define TUNGETFILTER _IOR('T', 219, struct sock_fprog)
+#define TUNGETRCVBUF _IOR('T', 220, int)
+#define TUNSETRCVBUF _IOW('T', 221, int)
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
--
1.8.3.2
--
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