[RFC,v4,0/4] several updates to virtio/vsock

  Hello,

this patchset evolved from previous v2 version (see link below). It does
several updates to virtio/vsock:
1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
   and 'rx_bytes', integer value is passed as an input argument. This
   makes code more simple, because in this case we don't need to update
   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
   more common words - we don't need to change skbuff state to update
   'rx_bytes' and 'fwd_cnt' correctly.
2) For SOCK_STREAM, when copying data to user fails, current skbuff is
   not dropped. Next read attempt will use same skbuff and last offset.
   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
   This behaviour was implemented before skbuff support.
3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
   this type of socket each skbuff is used only once: after removing it
   from socket's queue, it will be freed anyway.

Test for 2) also added:
Test tries to 'recv()' data to NULL buffer, then does 'recv()' with valid
buffer. For SOCK_STREAM second 'recv()' must return data, because skbuff
must not be dropped, but for SOCK_SEQPACKET skbuff will be dropped by
kernel, and 'recv()' will return EAGAIN.

Link to v1 on lore:
https://lore.kernel.org/netdev/c2d3e204-89d9-88e9-8a15-3fe027e56b4b@sberdevices.ru/

Link to v2 on lore:
https://lore.kernel.org/netdev/a7ab414b-5e41-c7b6-250b-e8401f335859@sberdevices.ru/

Link to v3 on lore:
https://lore.kernel.org/netdev/0abeec42-a11d-3a51-453b-6acf76604f2e@sberdevices.ru/

Change log:

v1 -> v2:
 - For SOCK_SEQPACKET call 'skb_pull()' also in case of copy failure or
   dropping skbuff (when we just waiting message end).
 - Handle copy failure for SOCK_STREAM in the same manner (plus free
   current skbuff).
 - Replace bug repdroducer with new test in vsock_test.c

v2 -> v3:
 - Replace patch which removes 'skb->len' subtraction from function
   'virtio_transport_dec_rx_pkt()' with patch which updates functions
   'virtio_transport_inc/dec_rx_pkt()' by passing integer argument
   instead of skbuff pointer.
 - Replace patch which drops skbuff when copying to user fails with
   patch which changes this behaviour by keeping skbuff in queue until
   it has no data.
 - Add patch for SOCK_SEQPACKET which removes redundant 'skb_pull()'
   call on read.
 - I remove "Fixes" tag from all patches, because all of them now change
   code logic, not only fix something.

v3 -> v4:
 - Update commit messages in all patches except test.
 - Add "Fixes" tag to all patches except test.

Arseniy Krasnov (4):
  virtio/vsock: don't use skbuff state to account credit
  virtio/vsock: remove redundant 'skb_pull()' call
  virtio/vsock: don't drop skbuff on copy failure
  test/vsock: copy to user failure test

 net/vmw_vsock/virtio_transport_common.c |  29 +++---
 tools/testing/vsock/vsock_test.c        | 118 ++++++++++++++++++++++++
 2 files changed, 131 insertions(+), 16 deletions(-)
  

Hi Arseniy,

On Thu, Mar 09, 2023 at 11:24:42PM +0300, Arseniy Krasnov wrote:
>Hello,
>
>this patchset evolved from previous v2 version (see link below). It does
>several updates to virtio/vsock:
>1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
>   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
>   and 'rx_bytes', integer value is passed as an input argument. This
>   makes code more simple, because in this case we don't need to update
>   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
>   more common words - we don't need to change skbuff state to update
>   'rx_bytes' and 'fwd_cnt' correctly.
>2) For SOCK_STREAM, when copying data to user fails, current skbuff is
>   not dropped. Next read attempt will use same skbuff and last offset.
>   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
>   This behaviour was implemented before skbuff support.
>3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
>   this type of socket each skbuff is used only once: after removing it
>   from socket's queue, it will be freed anyway.

thanks for the fixes, I would wait a few days to see if there are any
comments and then I think you can send it on net without RFC.

@Bobby if you can take a look, your ack would be appreciated :-)

Thanks,
Stefano
  

On 10.03.2023 12:09, Stefano Garzarella wrote:
> Hi Arseniy,
> 
> On Thu, Mar 09, 2023 at 11:24:42PM +0300, Arseniy Krasnov wrote:
>> Hello,
>>
>> this patchset evolved from previous v2 version (see link below). It does
>> several updates to virtio/vsock:
>> 1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
>>   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
>>   and 'rx_bytes', integer value is passed as an input argument. This
>>   makes code more simple, because in this case we don't need to update
>>   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
>>   more common words - we don't need to change skbuff state to update
>>   'rx_bytes' and 'fwd_cnt' correctly.
>> 2) For SOCK_STREAM, when copying data to user fails, current skbuff is
>>   not dropped. Next read attempt will use same skbuff and last offset.
>>   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
>>   This behaviour was implemented before skbuff support.
>> 3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
>>   this type of socket each skbuff is used only once: after removing it
>>   from socket's queue, it will be freed anyway.
> 
> thanks for the fixes, I would wait a few days to see if there are any
> comments and then I think you can send it on net without RFC.
> 
> @Bobby if you can take a look, your ack would be appreciated :-)
Ok, thanks for review. I'll wait for several days and also wait until
net-next will be opened. Then i'll resend this patchset with net-next

Thanks, Arseniy
> 
> Thanks,
> Stefano
>
  

On Fri, Mar 10, 2023 at 12:42:13PM +0300, Arseniy Krasnov wrote:
>
>
>On 10.03.2023 12:09, Stefano Garzarella wrote:
>> Hi Arseniy,
>>
>> On Thu, Mar 09, 2023 at 11:24:42PM +0300, Arseniy Krasnov wrote:
>>> Hello,
>>>
>>> this patchset evolved from previous v2 version (see link below). It does
>>> several updates to virtio/vsock:
>>> 1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
>>>   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
>>>   and 'rx_bytes', integer value is passed as an input argument. This
>>>   makes code more simple, because in this case we don't need to update
>>>   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
>>>   more common words - we don't need to change skbuff state to update
>>>   'rx_bytes' and 'fwd_cnt' correctly.
>>> 2) For SOCK_STREAM, when copying data to user fails, current skbuff is
>>>   not dropped. Next read attempt will use same skbuff and last offset.
>>>   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
>>>   This behaviour was implemented before skbuff support.
>>> 3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
>>>   this type of socket each skbuff is used only once: after removing it
>>>   from socket's queue, it will be freed anyway.
>>
>> thanks for the fixes, I would wait a few days to see if there are any
>> comments and then I think you can send it on net without RFC.
>>
>> @Bobby if you can take a look, your ack would be appreciated :-)
>Ok, thanks for review. I'll wait for several days and also wait until
>net-next will be opened. Then i'll resend this patchset with net-next

Since they are fixes, they should go with the net tree, not net-next.

Cheers,
Stefano
  

On 10.03.2023 14:40, Stefano Garzarella wrote:
> On Fri, Mar 10, 2023 at 12:42:13PM +0300, Arseniy Krasnov wrote:
>>
>>
>> On 10.03.2023 12:09, Stefano Garzarella wrote:
>>> Hi Arseniy,
>>>
>>> On Thu, Mar 09, 2023 at 11:24:42PM +0300, Arseniy Krasnov wrote:
>>>> Hello,
>>>>
>>>> this patchset evolved from previous v2 version (see link below). It does
>>>> several updates to virtio/vsock:
>>>> 1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
>>>>   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
>>>>   and 'rx_bytes', integer value is passed as an input argument. This
>>>>   makes code more simple, because in this case we don't need to update
>>>>   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
>>>>   more common words - we don't need to change skbuff state to update
>>>>   'rx_bytes' and 'fwd_cnt' correctly.
>>>> 2) For SOCK_STREAM, when copying data to user fails, current skbuff is
>>>>   not dropped. Next read attempt will use same skbuff and last offset.
>>>>   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
>>>>   This behaviour was implemented before skbuff support.
>>>> 3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
>>>>   this type of socket each skbuff is used only once: after removing it
>>>>   from socket's queue, it will be freed anyway.
>>>
>>> thanks for the fixes, I would wait a few days to see if there are any
>>> comments and then I think you can send it on net without RFC.
>>>
>>> @Bobby if you can take a look, your ack would be appreciated :-)
>> Ok, thanks for review. I'll wait for several days and also wait until
>> net-next will be opened. Then i'll resend this patchset with net-next
> 
> Since they are fixes, they should go with the net tree, not net-next.
Ah ok, for net tree i can send it no matter that net-next is closed.

Thanks, Arseniy
> 
> Cheers,
> Stefano
>