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Date: Fri, 6 Oct 2017 18:25:15 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: netdev@...r.kernel.org
Cc: mst@...hat.com, jasowang@...hat.com,
Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH RFC 2/3] tun: expand ethtool stats with zerocopy
From: Willem de Bruijn <willemb@...gle.com>
Add two counters to tun ethool stats to count zerocopy completions.
- tx_zerocopy counts completions that succeeded without copy.
- tx_zerocopy_err counts those that triggered a copy.
Tun intercepts completions by replacing the zerocopy completion
handler (ubuf_info) prepared by the packet source (vhost-net)
with its own.
To avoid adding another ubuf_info alloc/free in the datapath, only
enter this mode if the packet source passed an array of two ubuf_info
to the tun device.
Pass msg_controllen to tun_get_user to detect this.
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
drivers/net/tun.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 69 insertions(+), 10 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index df6ef9670d05..286787d8e875 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -149,6 +149,8 @@ struct tun_pcpu_stats {
u32 rx_dropped;
u32 tx_dropped;
u32 rx_frame_errors;
+ u64 tx_zerocopy;
+ u64 tx_zerocopy_err;
};
/* A tun_file connects an open character device to a tuntap netdevice. It
@@ -201,6 +203,8 @@ static const struct {
{ "tx_packets" },
{ "rx_bytes" },
{ "tx_bytes" },
+ { "tx_zerocopy" },
+ { "tx_zerocopy_err" },
};
/* Since the socket were moved to tun_file, to preserve the behavior of persist
@@ -1082,8 +1086,9 @@ static void tun_set_headroom(struct net_device *dev, int new_hr)
tun->align = new_hr;
}
-static void
-tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
+static void __tun_net_get_stats64(struct net_device *dev,
+ struct rtnl_link_stats64 *stats,
+ u64 *ethtool_stats)
{
u32 rx_dropped = 0, tx_dropped = 0, rx_frame_errors = 0;
struct tun_struct *tun = netdev_priv(dev);
@@ -1103,6 +1108,16 @@ tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
txbytes = p->tx_bytes;
} while (u64_stats_fetch_retry(&p->syncp, start));
+ if (ethtool_stats) {
+ ethtool_stats[0] += rxpackets;
+ ethtool_stats[1] += txpackets;
+ ethtool_stats[2] += rxbytes;
+ ethtool_stats[3] += txbytes;
+ ethtool_stats[4] += p->tx_zerocopy;
+ ethtool_stats[5] += p->tx_zerocopy_err;
+ continue;
+ }
+
stats->rx_packets += rxpackets;
stats->rx_bytes += rxbytes;
stats->tx_packets += txpackets;
@@ -1113,11 +1128,21 @@ tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
rx_frame_errors += p->rx_frame_errors;
tx_dropped += p->tx_dropped;
}
+
+ if (ethtool_stats)
+ return;
+
stats->rx_dropped = rx_dropped;
stats->rx_frame_errors = rx_frame_errors;
stats->tx_dropped = tx_dropped;
}
+static void tun_net_get_stats64(struct net_device *dev,
+ struct rtnl_link_stats64 *stats)
+{
+ __tun_net_get_stats64(dev, stats, NULL);
+}
+
static int tun_xdp_set(struct net_device *dev, struct bpf_prog *prog,
struct netlink_ext_ack *extack)
{
@@ -1537,10 +1562,44 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
return NULL;
}
+static void tun_zerocopy_callback(struct ubuf_info *ubuf, bool success)
+{
+ struct tun_struct *tun = ubuf->ctx;
+
+ if (success)
+ this_cpu_inc(tun->pcpu_stats->tx_zerocopy);
+ else
+ this_cpu_inc(tun->pcpu_stats->tx_zerocopy_err);
+
+ ubuf = ubuf - 1;
+ ubuf->callback(ubuf, success);
+}
+
+static void tun_set_zerocopy(struct tun_struct *tun, struct sk_buff *skb,
+ struct ubuf_info *ubuf, size_t len)
+{
+ const int ulen = sizeof(*ubuf);
+
+ if (len != ulen && len != ulen * 2) {
+ WARN_ON_ONCE(1);
+ return;
+ }
+
+ /* if caller passed two ubuf, one is for tun to interpose callback */
+ if (len == ulen * 2) {
+ ubuf = ubuf + 1;
+ ubuf->callback = tun_zerocopy_callback;
+ ubuf->ctx = tun;
+ refcount_set(&ubuf->refcnt, 1);
+ }
+
+ skb_shinfo(skb)->destructor_arg = ubuf;
+}
+
/* Get packet from user space buffer */
static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
- void *msg_control, struct iov_iter *from,
- int noblock, bool more)
+ void *msg_control, size_t msg_controllen,
+ struct iov_iter *from, int noblock, bool more)
{
struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
struct sk_buff *skb;
@@ -1713,7 +1772,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
/* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) {
- skb_shinfo(skb)->destructor_arg = msg_control;
+ tun_set_zerocopy(tun, skb, (void *)msg_control, msg_controllen);
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
} else if (msg_control) {
@@ -1798,7 +1857,7 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (!tun)
return -EBADFD;
- result = tun_get_user(tun, tfile, NULL, from,
+ result = tun_get_user(tun, tfile, NULL, 0, from,
file->f_flags & O_NONBLOCK, false);
tun_put(tun);
@@ -2058,7 +2117,8 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
if (!tun)
return -EBADFD;
- ret = tun_get_user(tun, tfile, m->msg_control, &m->msg_iter,
+ ret = tun_get_user(tun, tfile, m->msg_control, m->msg_controllen,
+ &m->msg_iter,
m->msg_flags & MSG_DONTWAIT,
m->msg_flags & MSG_MORE);
tun_put(tun);
@@ -2983,10 +3043,9 @@ static void tun_get_ethtool_stats(struct net_device *dev,
{
const int ethtool_stats_bytelen =
ARRAY_SIZE(tun_ethtool_stats_keys) * sizeof(u64);
- struct rtnl_link_stats64 link_stats64 = {0};
- tun_net_get_stats64(dev, &link_stats64);
- memcpy(data, &link_stats64, ethtool_stats_bytelen);
+ memset(data, 0, ethtool_stats_bytelen);
+ __tun_net_get_stats64(dev, NULL, data);
}
static const struct ethtool_ops tun_ethtool_ops = {
--
2.14.2.920.gcf0c67979c-goog
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