[SLOF] [PATCH v1 24/27] virtio-net: make net_hdr_size a variable

[Nikunj A Dadhania]

Alexey Kardashevskiy <aik at ozlabs.ru> writes:

> On 01/13/2016 10:17 PM, Nikunj A Dadhania wrote:
>> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
>> ---
>>   lib/libvirtio/virtio-net.c | 15 +++++++++------
>>   1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/lib/libvirtio/virtio-net.c b/lib/libvirtio/virtio-net.c
>> index 18ad2f7..9c51a39 100644
>> --- a/lib/libvirtio/virtio-net.c
>> +++ b/lib/libvirtio/virtio-net.c
>> @@ -53,6 +53,8 @@ struct virtio_net_hdr {
>>   	// uint16_t  num_buffers;	/* Only if VIRTIO_NET_F_MRG_RXBUF */
>>   };
>>
>> +static unsigned int net_hdr_size;
>
>
> Why? Just because sizeof(struct virtio_net_hdr) is longer? If so, then add 
> "const".

No, the net_hdr_size is different for legacy and modern device :-)

>
>
>
>> +
>>   static uint16_t last_rx_idx;	/* Last index in RX "used" ring */
>>
>>   /**
>> @@ -128,8 +130,9 @@ static int virtionet_init(net_driver_t *driver)
>>   	/* Device specific setup - we do not support special features right now */
>>   	virtio_set_guest_features(&virtiodev,  0);
>>
>> +	net_hdr_size = sizeof(struct virtio_net_hdr);
>>   	/* Allocate memory for one transmit an multiple receive buffers */
>> -	vq_rx.buf_mem = SLOF_alloc_mem((BUFFER_ENTRY_SIZE+sizeof(struct virtio_net_hdr))
>> +	vq_rx.buf_mem = SLOF_alloc_mem((BUFFER_ENTRY_SIZE+net_hdr_size)
>>   				   * RX_QUEUE_SIZE);
>
> Nit: I'd suggest wrapping after "+" and have both operands of "*" on the 
> same line.

Sure.

>
>
>
>>   	if (!vq_rx.buf_mem) {
>>   		printf("virtionet: Failed to allocate buffers!\n");
>> @@ -140,14 +143,14 @@ static int virtionet_init(net_driver_t *driver)
>>   	/* Prepare receive buffer queue */
>>   	for (i = 0; i < RX_QUEUE_SIZE; i++) {
>>   		uint64_t addr = (uint64_t)vq_rx.buf_mem
>> -			+ i * (BUFFER_ENTRY_SIZE+sizeof(struct virtio_net_hdr));
>> +			+ i * (BUFFER_ENTRY_SIZE+net_hdr_size);
>>   		uint32_t id = i*2;
>>   		/* Descriptor for net_hdr: */
>> -		fill_desc(&vq_rx.desc[id], 0, addr, sizeof(struct virtio_net_hdr),
>> +		fill_desc(&vq_rx.desc[id], 0, addr, net_hdr_size,
>>   			  VRING_DESC_F_NEXT | VRING_DESC_F_WRITE, id + 1);
>>
>>   		/* Descriptor for data: */
>> -		fill_desc(&vq_rx.desc[id+1], 0, addr + sizeof(struct virtio_net_hdr),
>> +		fill_desc(&vq_rx.desc[id+1], 0, addr + net_hdr_size,
>>   			  BUFFER_ENTRY_SIZE, VRING_DESC_F_WRITE, 0);
>>
>>   		vq_rx.avail->ring[i] = id;
>> @@ -221,7 +224,7 @@ static int virtionet_xmit(char *buf, int len)
>>
>>   	/* Set up virtqueue descriptor for header */
>>   	fill_desc(&vq_tx.desc[id], 0, (uint64_t)&nethdr,
>> -		  sizeof(struct virtio_net_hdr), VRING_DESC_F_NEXT, id + 1);
>> +		  net_hdr_size, VRING_DESC_F_NEXT, id + 1);
>>
>>   	/* Set up virtqueue descriptor for data */
>>   	fill_desc(&vq_tx.desc[id+1], 0, (uint64_t)buf, len, 0, 0);
>> @@ -254,7 +257,7 @@ static int virtionet_receive(char *buf, int maxlen)
>>   	id = (vq_rx.used->ring[last_rx_idx % vq_rx.size].id + 1)
>>   	     % vq_rx.size;
>>   	len = vq_rx.used->ring[last_rx_idx % vq_rx.size].len
>> -	      - sizeof(struct virtio_net_hdr);
>> +	      - net_hdr_size;
>>
>>   	dprintf("virtionet_receive() last_rx_idx=%i, vq_rx.used->idx=%i,"
>>   		" id=%i len=%i\n", last_rx_idx, vq_rx.used->idx, id, len);
>>
>
>
> -- 
> Alexey