[PATCH bpf-next v2 4/5] ethtool: don't allow disabling queues with umem installed

[Magnus Karlsson <magnus.karlsson@intel.com>]

From: Jakub Kicinski <jakub.kicinski@netronome.com>

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@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
---
 include/net/xdp_sock.h |  7 +++++++
 net/core/ethtool.c     | 11 +++++++++++
 net/xdp/xdp_umem.c     |  4 ++--
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 70a115b..13acb98 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -86,6 +86,7 @@ struct xdp_umem_fq_reuse *xsk_reuseq_prepare(u32 nentries);
 struct xdp_umem_fq_reuse *xsk_reuseq_swap(struct xdp_umem *umem,
 					  struct xdp_umem_fq_reuse *newq);
 void xsk_reuseq_free(struct xdp_umem_fq_reuse *rq);
+struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev, u16 queue_id);
 
 static inline char *xdp_umem_get_data(struct xdp_umem *umem, u64 addr)
 {
@@ -183,6 +184,12 @@ static inline void xsk_reuseq_free(struct xdp_umem_fq_reuse *rq)
 {
 }
 
+static inline struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
+						     u16 queue_id)
+{
+	return NULL;
+}
+
 static inline char *xdp_umem_get_data(struct xdp_umem *umem, u64 addr)
 {
 	return NULL;
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 9a648fb..5a788ad 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -27,6 +27,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/sched/signal.h>
 #include <linux/net.h>
+#include <net/xdp_sock.h>
 
 /*
  * Some useful ethtool_ops methods that're device independent.
@@ -1656,7 +1657,9 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 						   void __user *useraddr)
 {
 	struct ethtool_channels channels, curr = { .cmd = ETHTOOL_GCHANNELS };
+	u16 from_channel, to_channel;
 	u32 max_rx_in_use = 0;
+	unsigned int i;
 
 	if (!dev->ethtool_ops->set_channels || !dev->ethtool_ops->get_channels)
 		return -EOPNOTSUPP;
@@ -1680,6 +1683,14 @@ 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 */
+	from_channel = channels.combined_count +
+		min(channels.rx_count, channels.tx_count);
+	to_channel = curr.combined_count + max(curr.rx_count, curr.tx_count);
+	for (i = from_channel; i < to_channel; i++)
+		if (xdp_get_umem_from_qid(dev, i))
+			return -EINVAL;
+
 	return dev->ethtool_ops->set_channels(dev, &channels);
 }
 
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 4d6c665..773326f 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -55,8 +55,8 @@ static void xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
 		dev->_tx[queue_id].umem = umem;
 }
 
-static struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
-					      u16 queue_id)
+struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
+				       u16 queue_id)
 {
 	if (queue_id < dev->real_num_rx_queues)
 		return dev->_rx[queue_id].umem;
-- 
2.7.4