答复: [PATCH] net/virtio-user: support changing tap interface name

[Wenfeng Liu <liuwf@arraynetworks.com.cn>]

Hi Jianfeng,

At 2017-03-28 10:05:11, "Tan, Jianfeng" <jianfeng.tan@intel.com> wrote:
>Hi Wenfeng,
>
>Thank you for implementing this.
>
>On 3/11/2017 11:36 PM, Wenfeng Liu wrote:
>> This patch adds a new option 'iface' to change the interface name of
>> tap device with vhost-kernel as backend.
>>
>> Signed-off-by: Wenfeng Liu <liuwf@arraynetworks.com.cn>
>> ---
>>   drivers/net/virtio/virtio_user/virtio_user_dev.c | 12 ++++++++----
>>   drivers/net/virtio/virtio_user/virtio_user_dev.h |  2 +-
>>   drivers/net/virtio/virtio_user_ethdev.c          | 24
+++++++++++++++++++++---
>>   3 files changed, 30 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c
b/drivers/net/virtio/virtio_user/virtio_user_dev.c
>> index 21ed00d..e7fd65f 100644
>> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
>> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
>> @@ -193,9 +193,6 @@ int virtio_user_stop_device(struct virtio_user_dev
*dev)
>>   	for (i = 0; i < dev->max_queue_pairs; ++i)
>>   		dev->ops->enable_qp(dev, i, 0);
>>   
>> -	free(dev->ifname);
>> -	dev->ifname = NULL;
>
>If we do not free it here, we need to free it at virtio_user_pmd_remove().

Yes, I put the free in virtio_user_dev_uninit(), which will be called by
virtio_user_pmd_remove().

>
>> -
>>   	return 0;
>>   }
>>   
>> @@ -268,7 +265,7 @@ int virtio_user_stop_device(struct virtio_user_dev
*dev)
>>   
>>   int
>>   virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int
queues,
>> -		     int cq, int queue_size, const char *mac)
>> +		     int cq, int queue_size, const char *mac, char **ifname)
>>   {
>>   	snprintf(dev->path, PATH_MAX, "%s", path);
>>   	dev->max_queue_pairs = queues;
>> @@ -277,6 +274,11 @@ int virtio_user_stop_device(struct virtio_user_dev
*dev)
>>   	dev->mac_specified = 0;
>>   	parse_mac(dev, mac);
>>   
>> +	if (*ifname) {
>> +		dev->ifname = *ifname;
>> +		*ifname = NULL;
>> +	}
>> +
>>   	if (virtio_user_dev_setup(dev) < 0) {
>>   		PMD_INIT_LOG(ERR, "backend set up fails");
>>   		return -1;
>> @@ -327,6 +329,8 @@ int virtio_user_stop_device(struct virtio_user_dev
*dev)
>>   		free(dev->vhostfds);
>>   		free(dev->tapfds);
>>   	}
>> +
>> +	free(dev->ifname);

Here is the free in virtio_user_dev_uninit().

>>   }
>>   
>>   static uint8_t
>> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h
b/drivers/net/virtio/virtio_user/virtio_user_dev.h
>> index 0d39f40..6ecb91e 100644
>> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
>> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
>> @@ -69,7 +69,7 @@ struct virtio_user_dev {
>>   int virtio_user_start_device(struct virtio_user_dev *dev);
>>   int virtio_user_stop_device(struct virtio_user_dev *dev);
>>   int virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int
queues,
>> -			 int cq, int queue_size, const char *mac);
>> +			 int cq, int queue_size, const char *mac, char
**ifname);
>>   void virtio_user_dev_uninit(struct virtio_user_dev *dev);
>>   void virtio_user_handle_cq(struct virtio_user_dev *dev, uint16_t
queue_idx);
>>   #endif
>> diff --git a/drivers/net/virtio/virtio_user_ethdev.c
b/drivers/net/virtio/virtio_user_ethdev.c
>> index 0b226ac..16d1526 100644
>> --- a/drivers/net/virtio/virtio_user_ethdev.c
>> +++ b/drivers/net/virtio/virtio_user_ethdev.c
>> @@ -243,6 +243,8 @@
>>   	VIRTIO_USER_ARG_PATH,
>>   #define VIRTIO_USER_ARG_QUEUE_SIZE     "queue_size"
>>   	VIRTIO_USER_ARG_QUEUE_SIZE,
>> +#define VIRTIO_USER_ARG_INTERFACE_NAME "iface"
>> +	VIRTIO_USER_ARG_INTERFACE_NAME,
>>   	NULL
>>   };
>>   
>> @@ -259,6 +261,9 @@
>>   
>>   	*(char **)extra_args = strdup(value);
>>   
>> +	if (!*(char **)extra_args)
>> +		return -ENOMEM;
>> +
>>   	return 0;
>>   }
>>   
>> @@ -347,6 +352,7 @@
>>   	uint64_t cq = VIRTIO_USER_DEF_CQ_EN;
>>   	uint64_t queue_size = VIRTIO_USER_DEF_Q_SZ;
>>   	char *path = NULL;
>> +	char *ifname = NULL;
>>   	char *mac_addr = NULL;
>>   	int ret = -1;
>>   
>> @@ -375,6 +381,15 @@
>>   		goto end;
>>   	}
>>   
>> +	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_INTERFACE_NAME) == 1) {
>> +		if (rte_kvargs_process(kvlist,
VIRTIO_USER_ARG_INTERFACE_NAME,
>> +				       &get_string_arg, &ifname) < 0) {
>> +			PMD_INIT_LOG(ERR, "error to parse %s",
>> +				     VIRTIO_USER_ARG_INTERFACE_NAME);
>> +			goto end;
>> +		}
>> +	}
>> +
>>   	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_MAC) == 1) {
>>   		if (rte_kvargs_process(kvlist, VIRTIO_USER_ARG_MAC,
>>   				       &get_string_arg, &mac_addr) < 0) {
>> @@ -413,7 +428,7 @@
>>   		cq = 1;
>>   	}
>>   
>> -	if (queues > 1 && cq == 0) {
>> +	if (queues > 1 && cq == VIRTIO_USER_DEF_CQ_EN) {
>
>Any specific reason for above change? What if we set 
>VIRTIO_USER_DEF_CQ_EN=1 in future? I think zero is more clear.

Because cq was initialized to VIRTIO_USER_DEF_CQ_EN in this function, I
thought this comparison was intend to tell whether cq had been given a
different value, so I used 
VIRTIO_USER_DEF_CQ_EN instead the magic number 0. Did I understand this
correctly? If not, I am happy to change it back.
>
>Thanks,
>Jianfeng
>