Re: [dpdk-dev] [PATCH] ethdev: warn only once for badly behaving applications

["Ananyev, Konstantin" <konstantin.ananyev@intel.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:
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -610,7 +610,7 @@ eth_dev_configure_mp(uint16_t port_id, uint16_t
>   nb_rx_q, uint16_t nb_tx_q,
>  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>
> ---
>  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..7a5d05ff43 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_ref[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT];
> +static struct dummy_queue dummy_queues[RTE_MAX_ETHPORTS];
> +RTE_INIT(dummy_queue_init)
> +{
> +	uint16_t port_id;
> +
> +	for (port_id = 0; port_id < RTE_DIM(dummy_queues); port_id++) {
> +		unsigned int i;
> +
> +		for (i = 0; i < RTE_DIM(dummy_queues_ref[port_id]); i++)
> +			dummy_queues_ref[port_id][i] = &dummy_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 *q = rxq;
> +

LGTM in general, just one thing:
I think we'd better add extra check that rxq really points to dummy queues
before de-referencing it.
Something like:

uintptr_t port_id;
....
port_id =  q - dummy_queues;
if (port_id < RTE_DIM(dummy_queues) && !q->rx_warn_once) {
   ....
} 
 
Same for tx.

> +	if (!q->rx_warn_once) {
> +		uint16_t port_id = q - dummy_queues;
> +
> +		RTE_ETHDEV_LOG(ERR, "lcore %u called rx_pkt_burst for not ready port %"PRIu16"\n",
> +			rte_lcore_id(), port_id);
> +		rte_dump_stack();
> +		q->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 *q = txq;
> +
> +	if (!q->tx_warn_once) {
> +		uint16_t port_id = q - dummy_queues;
> +
> +		RTE_ETHDEV_LOG(ERR, "lcore %u called tx_pkt_burst for not ready port %"PRIu16"\n",
> +			rte_lcore_id(), port_id);
> +		rte_dump_stack();
> +		q->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 = {
> +	uint16_t port_id = fpo - rte_eth_fp_ops;
> +
> +	dummy_queues[port_id].rx_warn_once = false;
> +	dummy_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 = (struct rte_ethdev_qdata) {

Here and for txq, do we need to explicitly specify type?
Wouldn't:
.rxq = {.data=..., .clbk=...,},
be enough here?

> +			.data = (void **)&dummy_queues_ref[port_id],
> +			.clbk = dummy_data,
> +		},
> +		.txq = (struct rte_ethdev_qdata) {
> +			.data = (void **)&dummy_queues_ref[port_id],
> +			.clbk = dummy_data,
> +		},
>  	};
> -
> -	*fpo = dummy_ops;
>  }
> 
>  void
> --
> 2.23.0