[dpdk-dev] [PATCH v6 16/17] ethdev: convert to eal hotplug

[Shreyansh jain]

On Thursday 14 July 2016 10:21 PM, Jan Viktorin wrote:
> On Tue, 12 Jul 2016 11:31:21 +0530
> Shreyansh Jain <shreyansh.jain at nxp.com> wrote:
> 
>> Remove bus logic from ethdev hotplug by using eal for this.
>>
>> Current api is preserved:
>> - the last port that has been created is tracked to return it to the
>>   application when attaching,
>> - the internal device name is reused when detaching.
>>
>> We can not get rid of ethdev hotplug yet since we still need some mechanism
>> to inform applications of port creation/removal to substitute for ethdev
>> hotplug api.
>>
>> dev_type field in struct rte_eth_dev and rte_eth_dev_allocate are kept as
>> is, but this information is not needed anymore and is removed in the following
>> commit.
>>
>> Signed-off-by: David Marchand <david.marchand at 6wind.com>
>> Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
>> ---
>>  lib/librte_ether/rte_ethdev.c | 207 +++++++-----------------------------------
>>  1 file changed, 33 insertions(+), 174 deletions(-)
>>
>> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
>> index a667012..8d14fd7 100644
>> --- a/lib/librte_ether/rte_ethdev.c
>> +++ b/lib/librte_ether/rte_ethdev.c
>> @@ -72,6 +72,7 @@
>>  static const char *MZ_RTE_ETH_DEV_DATA = "rte_eth_dev_data";
>>  struct rte_eth_dev rte_eth_devices[RTE_MAX_ETHPORTS];
>>  static struct rte_eth_dev_data *rte_eth_dev_data;
>> +static uint8_t eth_dev_last_created_port;
>>  static uint8_t nb_ports;
>>  
> 
> [...]
> 
>> -
>>  /* attach the new device, then store port_id of the device */
>>  int
>>  rte_eth_dev_attach(const char *devargs, uint8_t *port_id)
>>  {
>> -	struct rte_pci_addr addr;
>>  	int ret = -1;
>> +	int current = eth_dev_last_created_port;
>> +	char *name = NULL;
>> +	char *args = NULL;
>>  
>>  	if ((devargs == NULL) || (port_id == NULL)) {
>>  		ret = -EINVAL;
>>  		goto err;
>>  	}
>>  
>> -	if (eal_parse_pci_DomBDF(devargs, &addr) == 0) {
>> -		ret = rte_eth_dev_attach_pdev(&addr, port_id);
>> -		if (ret < 0)
>> -			goto err;
>> -	} else {
>> -		ret = rte_eth_dev_attach_vdev(devargs, port_id);
>> -		if (ret < 0)
>> -			goto err;
>> +	/* parse devargs, then retrieve device name and args */
>> +	if (rte_eal_parse_devargs_str(devargs, &name, &args))
>> +		goto err;
>> +
>> +	ret = rte_eal_dev_attach(name, args);
>> +	if (ret < 0)
>> +		goto err;
>> +
>> +	/* no point looking at eth_dev_last_created_port if no port exists */
> 
> I am not sure about this comment. What is "no point"?
> 
> Isn't this also a potential bug? (Like the one below.) How could it
> happen there is no port after a successful attach?

Yes, even searching through code path I couldn't find a positive case where control would reach here without nb_ports>0.
Though, i am not sure if some rough application attempts to mix-up calls - and that, in my opinion, is not worth checking.
Should I remove it?

> 
>> +	if (!nb_ports) {
>> +		ret = -1;
>> +		goto err;
>> +	}
>> +	/* if nothing happened, there is a bug here, since some driver told us
>> +	 * it did attach a device, but did not create a port */
>> +	if (current == eth_dev_last_created_port) {
>> +		ret = -1;
>> +		goto err;
> 
> Should we log this? Or call some kind panic?

I will place a log because applications should have a chance to ignore a device which cannot be attached for whatever reason.

> 
>>  	}
>> +	*port_id = eth_dev_last_created_port;
>> +	ret = 0;
>>  
>> -	return 0;
>>  err:
>> -	RTE_LOG(ERR, EAL, "Driver, cannot attach the device\n");
>> +	free(name);
>> +	free(args);
>>  	return ret;
>>  }
>>  
>> @@ -590,7 +464,6 @@ err:
>>  int
>>  rte_eth_dev_detach(uint8_t port_id, char *name)
>>  {
>> -	struct rte_pci_addr addr;
>>  	int ret = -1;
>>  
>>  	if (name == NULL) {
>> @@ -598,33 +471,19 @@ rte_eth_dev_detach(uint8_t port_id, char *name)
>>  		goto err;
>>  	}
>>  
>> -	/* check whether the driver supports detach feature, or not */
>> +	/* FIXME: move this to eal, once device flags are relocated there */
>>  	if (rte_eth_dev_is_detachable(port_id))
>>  		goto err;
>>  
>> -	if (rte_eth_dev_get_device_type(port_id) == RTE_ETH_DEV_PCI) {
>> -		ret = rte_eth_dev_get_addr_by_port(port_id, &addr);
>> -		if (ret < 0)
>> -			goto err;
>> -
>> -		ret = rte_eth_dev_detach_pdev(port_id, &addr);
>> -		if (ret < 0)
>> -			goto err;
>> -
>> -		snprintf(name, RTE_ETH_NAME_MAX_LEN,
>> -			"%04x:%02x:%02x.%d",
>> -			addr.domain, addr.bus,
>> -			addr.devid, addr.function);
>> -	} else {
>> -		ret = rte_eth_dev_detach_vdev(port_id, name);
>> -		if (ret < 0)
>> -			goto err;
>> -	}
>> +	snprintf(name, sizeof(rte_eth_devices[port_id].data->name),
>> +		 "%s", rte_eth_devices[port_id].data->name);
>> +	ret = rte_eal_dev_detach(name);
>> +	if (ret < 0)
>> +		goto err;
>>  
>>  	return 0;
>>  
>>  err:
>> -	RTE_LOG(ERR, EAL, "Driver, cannot detach the device\n");
> 
> I'd be more specific about the failing device, we have its name.

Agree. I will add 'name' to this.

>>  	return ret;
>>  }
>>
>