[PATCH] net/af_packet: fix socket close on device stop

[Tudor Cornea <tudor.cornea@gmail.com>]

Currently, if we call rte_eth_dev_stop(), the sockets are closed.
If we attempt to start the port again, socket related operations
will not work correctly.

This can be alleviated by closing the socket at the same place in
which we currently free the memory, in eth_dev_close().

If an application calls rte_eth_dev_stop() on a port managed
by the af_packet PMD, the port becomes unusable. This is in contrast
with ports managed by other drivers (e.g virtio).

I also managed to reproduce the issue using testpmd.

sudo ip link add test-veth0 type veth peer name test-veth1

sudo ip link set test-veth0 up
sudo ip link set test-veth1 up

AF_PACKET_ARGS=\
"blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0"

sudo ./dpdk-testpmd \
        -l 0-3 \
        -m 1024 \
        --no-huge \
        --no-shconf \
        --no-pci \
        --vdev=net_af_packet0,iface=test-veth0,${AF_PACKET_ARGS} \
        --vdev=net_af_packet1,iface=test-veth1,${AF_PACKET_ARGS} \
        -- \
        -i

testpmd> start tx_first

Forwarding will start, and we will see traffic on the interfaces.

testpmd> stop
testpmd> port stop 0
Stopping ports...
Checking link statuses...
Done
testpmd> port stop 1
Stopping ports...
Checking link statuses...
Done

testpmd> port start 0
AFPACKET: eth_dev_macaddr_set(): receive socket not found
Port 0: CA:65:81:63:81:B2
Checking link statuses...
Done
testpmd> port start 1
AFPACKET: eth_dev_macaddr_set(): receive socket not found
Port 1: CA:12:D0:BE:93:3F
Checking link statuses...
Done

testpmd> start tx_first

When we start forwarding again, we can see that there is no traffic
on the interfaces. This does not happen when testing with other PMD
drivers (e.g virtio).

With the patch, the port should re-initialize correctly.

testpmd> port start 0
Port 0: CA:65:81:63:81:B2
Checking link statuses...
Done

Fixes: 364e08f2bbc0 ("af_packet: add PMD for AF_PACKET-based virtual devices")

Signed-off-by: Tudor Cornea <tudor.cornea@gmail.com>
---
 drivers/net/af_packet/rte_eth_af_packet.c | 30 +++++++++++------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
index ceb8d9356a..efae15a493 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -357,27 +357,12 @@ static int
 eth_dev_stop(struct rte_eth_dev *dev)
 {
 	unsigned i;
-	int sockfd;
 	struct pmd_internals *internals = dev->data->dev_private;
 
 	for (i = 0; i < internals->nb_queues; i++) {
-		sockfd = internals->rx_queue[i].sockfd;
-		if (sockfd != -1)
-			close(sockfd);
-
-		/* Prevent use after free in case tx fd == rx fd */
-		if (sockfd != internals->tx_queue[i].sockfd) {
-			sockfd = internals->tx_queue[i].sockfd;
-			if (sockfd != -1)
-				close(sockfd);
-		}
-
-		internals->rx_queue[i].sockfd = -1;
-		internals->tx_queue[i].sockfd = -1;
 		dev->data->rx_queue_state[i] = RTE_ETH_QUEUE_STATE_STOPPED;
 		dev->data->tx_queue_state[i] = RTE_ETH_QUEUE_STATE_STOPPED;
 	}
-
 	dev->data->dev_link.link_status = RTE_ETH_LINK_DOWN;
 	return 0;
 }
@@ -474,6 +459,7 @@ eth_dev_close(struct rte_eth_dev *dev)
 	struct pmd_internals *internals;
 	struct tpacket_req *req;
 	unsigned int q;
+	int sockfd;
 
 	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
 		return 0;
@@ -484,6 +470,20 @@ eth_dev_close(struct rte_eth_dev *dev)
 	internals = dev->data->dev_private;
 	req = &internals->req;
 	for (q = 0; q < internals->nb_queues; q++) {
+		sockfd = internals->rx_queue[q].sockfd;
+		if (sockfd != -1)
+			close(sockfd);
+
+		/* Prevent use after free in case tx fd == rx fd */
+		if (sockfd != internals->tx_queue[q].sockfd) {
+			sockfd = internals->tx_queue[q].sockfd;
+			if (sockfd != -1)
+				close(sockfd);
+		}
+
+		internals->rx_queue[q].sockfd = -1;
+		internals->tx_queue[q].sockfd = -1;
+
 		munmap(internals->rx_queue[q].map,
 			2 * req->tp_block_size * req->tp_block_nr);
 		rte_free(internals->rx_queue[q].rd);
-- 
2.34.1