netdev - [RFC bpf-next 6/6] ethtool: don't allow disabling queues with umem installed

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Date:   Thu, 26 Jul 2018 14:41:48 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net,
        brouer@...hat.com,
        Björn Töpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [RFC bpf-next 6/6] ethtool: don't allow disabling queues with umem installed

We already check the RSS indirection table does not use queues
which would be disabled by channel reconfiguration.  Make sure
user does not try to disable queues which have a UMEM and zero-
-copy AF_XDP socket installed.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
 include/linux/netdevice.h | 8 ++++++++
 net/core/ethtool.c        | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a5a34f0fb485..c0df40deec54 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3566,7 +3566,15 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 		      int fd, u32 flags);
 u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
 		    enum bpf_netdev_command cmd);
+
+#if defined(CONFIG_XDP_SOCKETS)
 int xdp_umem_query(struct net_device *dev, u16 queue_id);
+#else
+static inline int xdp_umem_query(struct net_device *dev, u16 queue_id)
+{
+	return 0;
+}
+#endif
 
 int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
 int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 4d5093577fe6..a8e693de5b11 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1745,6 +1745,7 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 {
 	struct ethtool_channels channels, curr = { .cmd = ETHTOOL_GCHANNELS };
 	u32 max_rx_in_use = 0;
+	unsigned int i;
 
 	if (!dev->ethtool_ops->set_channels || !dev->ethtool_ops->get_channels)
 		return -EOPNOTSUPP;
@@ -1768,6 +1769,12 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 	    (channels.combined_count + channels.rx_count) <= max_rx_in_use)
 	    return -EINVAL;
 
+	/* Disabling channels, query zero-copy AF_XDP sockets */
+	for (i = channels.combined_count + channels.rx_count;
+	     i < curr.combined_count + curr.rx_count; i++)
+		if (xdp_umem_query(dev, i) > 0)
+			return -EINVAL;
+
 	return dev->ethtool_ops->set_channels(dev, &channels);
 }
 
-- 
2.17.1