Re: [dpdk-dev] [PATCH 2/2] app/testpmd: fix hot-unplug detaching

[Matan Azrad <matan@mellanox.com>]

Hi Thomas

Thanks for the patches, I Saw it just now.
 please see small comment below:

 From: Thomas Monjalon
> There is a possible race condition in the hotplug path in rmv_port_callback().
> If a port is created between
> close_port(port_id) and detach_port_device(port_id), then the port_id will
> have been reallocated to a different device which will be wrongly detached.
> 
> Since a check was added in detach_port_device() for manual detach case,
> the hotplug path was even more broken.
> It became impossible to run because the new check prevented to run
> detach_port_device() after the port is closed.
> 
> The solution for both issues is to not rely on the port_id for detaching the
> rte_device.
> The function detach_port_device() is split to allow calling
> detach_device() directly with the rte_device pointer, saved before closing
> the port.
> 
> Fixes: 43d0e304980a ("app/testpmd: fix invalid port detaching")

If you fix the race, Don't you think you need to add fixes line for the patch which created the race?

> Cc: stable@dpdk.org
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
>  app/test-pmd/testpmd.c | 48 ++++++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 20 deletions(-)
> 
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c index
> 11203cb03d..035836adfb 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -2633,32 +2633,17 @@ setup_attached_port(portid_t pi)
>  	printf("Done\n");
>  }
> 
> -void
> -detach_port_device(portid_t port_id)
> +static void
> +detach_device(struct rte_device *dev)
>  {
> -	struct rte_device *dev;
>  	portid_t sibling;
> 
> -	printf("Removing a device...\n");
> -
> -	if (port_id_is_invalid(port_id, ENABLED_WARN))
> -		return;
> -
> -	dev = rte_eth_devices[port_id].device;
>  	if (dev == NULL) {
>  		printf("Device already removed\n");
>  		return;
>  	}
> 
> -	if (ports[port_id].port_status != RTE_PORT_CLOSED) {
> -		if (ports[port_id].port_status != RTE_PORT_STOPPED) {
> -			printf("Port not stopped\n");
> -			return;
> -		}
> -		printf("Port was not closed\n");
> -		if (ports[port_id].flow_list)
> -			port_flow_flush(port_id);
> -	}
> +	printf("Removing a device...\n");
> 
>  	if (rte_dev_remove(dev) < 0) {
>  		TESTPMD_LOG(ERR, "Failed to detach device %s\n", dev-
> >name); @@ -2676,13 +2661,31 @@ detach_port_device(portid_t port_id)
> 
>  	remove_invalid_ports();
> 
> -	printf("Device of port %u is detached\n", port_id);
> +	printf("Device is detached\n");
>  	printf("Now total ports is %d\n", nb_ports);
>  	printf("Done\n");
>  	return;
>  }
> 
>  void
> +detach_port_device(portid_t port_id)
> +{
> +	if (port_id_is_invalid(port_id, ENABLED_WARN))
> +		return;
> +
> +	if (ports[port_id].port_status != RTE_PORT_CLOSED) {
> +		if (ports[port_id].port_status != RTE_PORT_STOPPED) {
> +			printf("Port not stopped\n");
> +			return;
> +		}
> +		printf("Port was not closed\n");
> +		if (ports[port_id].flow_list)
> +			port_flow_flush(port_id);
> +	}
> +
> +	detach_device(rte_eth_devices[port_id].device);
> +}
> +
>  void
>  detach_devargs(char *identifier)
>  {
> @@ -2873,6 +2876,7 @@ rmv_port_callback(void *arg)
>  	int need_to_start = 0;
>  	int org_no_link_check = no_link_check;
>  	portid_t port_id = (intptr_t)arg;
> +	struct rte_device *dev;
> 
>  	RTE_ETH_VALID_PORTID_OR_RET(port_id);
> 
> @@ -2883,8 +2887,12 @@ rmv_port_callback(void *arg)
>  	no_link_check = 1;
>  	stop_port(port_id);
>  	no_link_check = org_no_link_check;
> +
> +	/* Save rte_device pointer before closing ethdev port */
> +	dev = rte_eth_devices[port_id].device;
>  	close_port(port_id);
> -	detach_port_device(port_id);
> +	detach_device(dev); /* might be already removed or have more
> ports */
> +
>  	if (need_to_start)
>  		start_packet_forwarding(0);
>  }
> --
> 2.25.0