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From: Arseniy Krasnov <avkrasnov@sberdevices.ru>
To: Stefano Garzarella <sgarzare@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Bobby Eshleman <bobby.eshleman@bytedance.com>,
	<kvm@vger.kernel.org>,
	<virtualization@lists.linux-foundation.org>,
	<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<kernel@sberdevices.ru>, <oxffffaa@gmail.com>
Subject: Re: [RFC PATCH v3 0/4] several updates to virtio/vsock
Date: Thu, 9 Mar 2023 23:34:09 +0300	[thread overview]
Message-ID: <b0fe0f25-42d0-f51b-423d-0d1fb724b53d@sberdevices.ru> (raw)
In-Reply-To: <20230309163200.lq6dzop724diafpf@sgarzare-redhat>



On 09.03.2023 19:32, Stefano Garzarella wrote:
> On Thu, Mar 09, 2023 at 07:20:20PM +0300, Arseniy Krasnov wrote:
>>
>>
>> On 09.03.2023 19:21, Stefano Garzarella wrote:
>>> On Thu, Mar 09, 2023 at 01:10:36PM +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 udpate
>>>>   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/
>>>>
>>>> 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.
>>>
>>> Yes, but they solve the problem, so we should use the tag (I think at
>>> least in patch 1 and 3).
>>>
>>> We usually use the tag when we are fixing a problem introduced by a
>>> previous change. So we need to backport the patch to the stable branches
>>> as well, and we need the tag to figure out which branches have the patch
>>> or not.
>> Ahh, sorry. Ok. I see now :)
> 
> No problem at all :-)
> 
> I think also patch 2 can have the Fixes tag.
> 
Done, fixed everything in v4.

Thanks, Arseniy

> Thanks,
> Stefano
> 
>>
>> Thanks, Arseniy
>>>
>>> Thanks,
>>> Stefano
>>>
>>>>
>>>> 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(-)
>>>>
>>>> -- 
>>>> 2.25.1
>>>>
>>>
>>
> 

      reply	other threads:[~2023-03-09 20:37 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-09 10:10 [RFC PATCH v3 0/4] several updates to virtio/vsock Arseniy Krasnov
2023-03-09 10:11 ` [RFC PATCH v3 1/4] virtio/vsock: don't use skbuff state to account credit Arseniy Krasnov
2023-03-09 16:27   ` Stefano Garzarella
2023-03-09 10:12 ` [RFC PATCH v3 2/4] virtio/vsock: remove redundant 'skb_pull()' call Arseniy Krasnov
2023-03-09 16:29   ` Stefano Garzarella
2023-03-09 10:13 ` [RFC PATCH v3 3/4] virtio/vsock: don't drop skbuff on copy failure Arseniy Krasnov
2023-03-09 16:30   ` Stefano Garzarella
2023-03-09 10:14 ` [RFC PATCH v3 4/4] test/vsock: copy to user failure test Arseniy Krasnov
2023-03-09 16:30   ` Stefano Garzarella
2023-03-09 16:21 ` [RFC PATCH v3 0/4] several updates to virtio/vsock Stefano Garzarella
2023-03-09 16:20   ` Arseniy Krasnov
2023-03-09 16:32     ` Stefano Garzarella
2023-03-09 20:34       ` Arseniy Krasnov [this message]

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