Re: [dpdk-dev] [PATCH] examples/kni: fix crash while handling userspace request

["Phil Yang (Arm Technology China)" <Phil.Yang@arm.com>]

Hi Ferruh,

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Wednesday, January 16, 2019 1:28 AM
> To: dev@dpdk.org
> Cc: stable@dpdk.org; he.qiao17@zte.com.cn; Igor Ryzhov
> <iryzhov@nfware.com>; Phil Yang (Arm Technology China)
> <Phil.Yang@arm.com>; Dan Gora <dg@adax.com>
> Subject: [PATCH] examples/kni: fix crash while handling userspace request
>
> When KNI interface receives RTE_KNI_REQ_CFG_NETWORK_IF request, it
> stap/start the physical device which as a result of stop() can free all the mbufs in
> its queue.
> Meanwhile sample application continues to read from KNI interface queues and
> push into device queues. This simultaneous access may cause a crash, crash log
> can be found at defect description.
>
> As a solution KNI sample application can do the proper synchronization, and
> stop transfer between KNI interface and physical interface while physical device
> stop/started.
>
> Bugzilla ID: 116
> Fixes: 3fc5ca2f6352 ("kni: initial import")
> Cc: stable@dpdk.org
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> ---
> Cc: he.qiao17@zte.com.cn
> I am not able to re-produce the defect can you please test with this patch?
>
> And another concern is performance affect of this patch, new check is added
> into fast path. Cc'ed a few more people for comment:
> Cc: Igor Ryzhov <iryzhov@nfware.com>
> Cc: Phil Yang <phil.yang@arm.com>
> Cc: Dan Gora <dg@adax.com>
> ---
>  examples/kni/main.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/examples/kni/main.c b/examples/kni/main.c index
> c468ffd19..a8ce07e2a 100644
> --- a/examples/kni/main.c
> +++ b/examples/kni/main.c
> @@ -132,6 +132,7 @@ static int kni_config_network_interface(uint16_t port_id,
> uint8_t if_up);  static int kni_config_mac_address(uint16_t port_id, uint8_t
> mac_addr[]);
>
>  static rte_atomic32_t kni_stop = RTE_ATOMIC32_INIT(0);
> +static rte_atomic32_t kni_pause = RTE_ATOMIC32_INIT(0);
>
>  /* Print out statistics on packets handled */  static void @@ -276,6 +277,7 @@
> main_loop(__rte_unused void *arg)  {
>  uint16_t i;
>  int32_t f_stop;
> +int32_t f_pause;
>  const unsigned lcore_id = rte_lcore_id();
>  enum lcore_rxtx {
>  LCORE_NONE,
> @@ -304,8 +306,11 @@ main_loop(__rte_unused void *arg)
>  kni_port_params_array[i]->port_id);
>  while (1) {
>  f_stop = rte_atomic32_read(&kni_stop);
> +f_pause = rte_atomic32_read(&kni_pause);
>  if (f_stop)
>  break;
> +if (f_pause)
> +continue;
>  kni_ingress(kni_port_params_array[i]);
>  }
>  } else if (flag == LCORE_TX) {
> @@ -314,8 +319,11 @@ main_loop(__rte_unused void *arg)
>  kni_port_params_array[i]->port_id);
>  while (1) {
>  f_stop = rte_atomic32_read(&kni_stop);
> +f_pause = rte_atomic32_read(&kni_pause);
>  if (f_stop)
>  break;
> +if (f_pause)
> +continue;
>  kni_egress(kni_port_params_array[i]);
>  }
>  } else
> @@ -807,12 +815,16 @@ kni_config_network_interface(uint16_t port_id,
> uint8_t if_up)
>  RTE_LOG(INFO, APP, "Configure network interface of %d %s\n",
>  port_id, if_up ? "up" : "down");
>
> +rte_atomic32_inc(&kni_pause);
> +
>  if (if_up != 0) { /* Configure network interface up */
>  rte_eth_dev_stop(port_id);
>  ret = rte_eth_dev_start(port_id);
>  } else /* Configure network interface down */
>  rte_eth_dev_stop(port_id);
>
> +rte_atomic32_dec(&kni_pause);
> +
>  if (ret < 0)
>  RTE_LOG(ERR, APP, "Failed to start port %d\n", port_id);
>
> --
> 2.17.2

Acked-by: Phil Yang <phil.yang@arm.com>

Thanks,
Phil Yang
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