[dpdk-dev] [PATCH v2] ethdev: warn once for buggy applications

[David Marchand <david.marchand@redhat.com>]

Warning continuously is a pain when developping or if a unit test
is/gets broken.

It could also be a problem if application behaves badly only in some
corner cases and a DoS results of those logs being continuously displayed.

Let's warn once per port and per rx/tx.

Getting such a log is scary, but let's make it more eye catching by
dumping a backtrace with it.

Tested by introducing a bug in testpmd:
 static int
 eth_dev_start_mp(uint16_t port_id)
 {
-       if (is_proc_primary())
+       if (!is_proc_primary())
                return rte_eth_dev_start(port_id);

        return 0;

Then, running a basic null test:
$ ./devtools/test-null.sh
...
Start automatic packet forwarding
io packet forwarding - ports=2 - cores=1 - streams=2 - NUMA support
  enabled, MP allocation mode: native
Logical Core 1 (socket 0) forwards packets on 2 streams:
  RX P=0/Q=0 (socket 0) -> TX P=1/Q=0 (socket 0) peer=02:00:00:00:00:01
  RX P=1/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=02:00:00:00:00:00

lcore 0 called rx_pkt_burst for not ready port 0
8: [build/app/dpdk-testpmd() [0x59e839]]
7: [/lib64/libc.so.6(__libc_start_main+0xf5) [0x7ff481b69555]]
6: [build/app/dpdk-testpmd(main+0x54b) [0x662d24]]
5: [build/app/dpdk-testpmd(start_packet_forwarding+0x263) [0x65e795]]
4: [build/app/dpdk-testpmd() [0x65e1be]]
3: [build/app/dpdk-testpmd() [0x65a996]]
2: [build/app/dpdk-testpmd() [0xa6cbc7]]
1: [build/app/dpdk-testpmd(rte_dump_stack+0x27) [0xaee796]]
lcore 0 called rx_pkt_burst for not ready port 1
8: [build/app/dpdk-testpmd() [0x59e839]]
7: [/lib64/libc.so.6(__libc_start_main+0xf5) [0x7ff481b69555]]
6: [build/app/dpdk-testpmd(main+0x54b) [0x662d24]]
5: [build/app/dpdk-testpmd(start_packet_forwarding+0x263) [0x65e795]]
4: [build/app/dpdk-testpmd() [0x65e1be]]
3: [build/app/dpdk-testpmd() [0x65a996]]
2: [build/app/dpdk-testpmd() [0xa6cbc7]]
1: [build/app/dpdk-testpmd(rte_dump_stack+0x27) [0xaee796]]
  io packet forwarding packets/burst=32
  nb forwarding cores=1 - nb forwarding ports=2
  port 0: RX queue number: 1 Tx queue number: 1
    Rx offloads=0x0 Tx offloads=0x0

Fixes: c87d435a4d79 ("ethdev: copy fast-path API into separate structure")

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
Changes since v1:
- removed diff banner in commitlog,
- renamed vars,
- removed unneeded cast on anonymous struct in initialisation construct,
- added check on queue pointer,

---
 lib/ethdev/ethdev_private.c | 63 +++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 9 deletions(-)

diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
index c905c2df6f..8fca20c7d4 100644
--- a/lib/ethdev/ethdev_private.c
+++ b/lib/ethdev/ethdev_private.c
@@ -2,6 +2,7 @@
  * Copyright(c) 2018 Gaëtan Rivet
  */
 
+#include <rte_debug.h>
 #include "rte_ethdev.h"
 #include "ethdev_driver.h"
 #include "ethdev_private.h"
@@ -175,22 +176,58 @@ rte_eth_devargs_parse_representor_ports(char *str, void *data)
 	return str == NULL ? -1 : 0;
 }
 
+struct dummy_queue {
+	bool rx_warn_once;
+	bool tx_warn_once;
+};
+static struct dummy_queue *dummy_queues_array[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT];
+static struct dummy_queue per_port_queues[RTE_MAX_ETHPORTS];
+RTE_INIT(dummy_queue_init)
+{
+	uint16_t port_id;
+
+	for (port_id = 0; port_id < RTE_DIM(per_port_queues); port_id++) {
+		unsigned int q;
+
+		for (q = 0; q < RTE_DIM(dummy_queues_array[port_id]); q++)
+			dummy_queues_array[port_id][q] = &per_port_queues[port_id];
+	}
+}
+
 static uint16_t
-dummy_eth_rx_burst(__rte_unused void *rxq,
+dummy_eth_rx_burst(void *rxq,
 		__rte_unused struct rte_mbuf **rx_pkts,
 		__rte_unused uint16_t nb_pkts)
 {
-	RTE_ETHDEV_LOG(ERR, "rx_pkt_burst for not ready port\n");
+	struct dummy_queue *queue = rxq;
+	uintptr_t port_id;
+
+	port_id = queue - per_port_queues;
+	if (port_id < RTE_DIM(per_port_queues) && !queue->rx_warn_once) {
+		RTE_ETHDEV_LOG(ERR, "lcore %u called rx_pkt_burst for not ready port %"PRIuPTR"\n",
+			rte_lcore_id(), port_id);
+		rte_dump_stack();
+		queue->rx_warn_once = true;
+	}
 	rte_errno = ENOTSUP;
 	return 0;
 }
 
 static uint16_t
-dummy_eth_tx_burst(__rte_unused void *txq,
+dummy_eth_tx_burst(void *txq,
 		__rte_unused struct rte_mbuf **tx_pkts,
 		__rte_unused uint16_t nb_pkts)
 {
-	RTE_ETHDEV_LOG(ERR, "tx_pkt_burst for not ready port\n");
+	struct dummy_queue *queue = txq;
+	uintptr_t port_id;
+
+	port_id = queue - per_port_queues;
+	if (port_id < RTE_DIM(per_port_queues) && !queue->tx_warn_once) {
+		RTE_ETHDEV_LOG(ERR, "lcore %u called tx_pkt_burst for not ready port %"PRIuPTR"\n",
+			rte_lcore_id(), port_id);
+		rte_dump_stack();
+		queue->tx_warn_once = true;
+	}
 	rte_errno = ENOTSUP;
 	return 0;
 }
@@ -199,14 +236,22 @@ void
 eth_dev_fp_ops_reset(struct rte_eth_fp_ops *fpo)
 {
 	static void *dummy_data[RTE_MAX_QUEUES_PER_PORT];
-	static const struct rte_eth_fp_ops dummy_ops = {
+	uintptr_t port_id = fpo - rte_eth_fp_ops;
+
+	per_port_queues[port_id].rx_warn_once = false;
+	per_port_queues[port_id].tx_warn_once = false;
+	*fpo = (struct rte_eth_fp_ops) {
 		.rx_pkt_burst = dummy_eth_rx_burst,
 		.tx_pkt_burst = dummy_eth_tx_burst,
-		.rxq = {.data = dummy_data, .clbk = dummy_data,},
-		.txq = {.data = dummy_data, .clbk = dummy_data,},
+		.rxq = {
+			.data = (void **)&dummy_queues_array[port_id],
+			.clbk = dummy_data,
+		},
+		.txq = {
+			.data = (void **)&dummy_queues_array[port_id],
+			.clbk = dummy_data,
+		},
 	};
-
-	*fpo = dummy_ops;
 }
 
 void
-- 
2.23.0