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Message-ID: <64451c35-5442-73cb-4398-2b907dd810cc@sberdevices.ru>
Date:   Tue, 28 Mar 2023 14:20:33 +0300
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Subject: Re: [RFC PATCH v1 1/2] vsock: return errors other than -ENOMEM to
 socket
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To:     Stefano Garzarella <sgarzare@redhat.com>,
        Vishnu Dasa <vdasa@vmware.com>
CC:     Bryan Tan <bryantan@vmware.com>,
        VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
        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>
References: <97f19214-ba04-c47e-7486-72e8aa16c690@sberdevices.ru>
 <99da938b-3e67-150c-2f74-41d917a95950@sberdevices.ru>
 <itjmw7vh3a7ggbodsu4mksu2hqbpdpxmu6cpexbra66nfhsw4x@hzpuzwldkfx5>
 <CAGxU2F648TyvAJN+Zk6YCnGUhn=0W_MZTox7RxQ45zHmHHO0SA@mail.gmail.com>
 <0f0a8603-e8a1-5fb2-23d9-5773c808ef85@sberdevices.ru>
 <ak74j6l2qesrixxmw7pfw56najqhdn32lv3xfxcb53nvmkyi3x@fr25vo2jlvbj>
From:   Arseniy Krasnov <avkrasnov@sberdevices.ru>
In-Reply-To: <ak74j6l2qesrixxmw7pfw56najqhdn32lv3xfxcb53nvmkyi3x@fr25vo2jlvbj>
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On 28.03.2023 14:19, Stefano Garzarella wrote:
> On Tue, Mar 28, 2023 at 01:42:19PM +0300, Arseniy Krasnov wrote:
>>
>>
>> On 28.03.2023 12:42, Stefano Garzarella wrote:
>>> I pressed send too early...
>>>
>>> CCing Bryan, Vishnu, and pv-drivers@vmware.com
>>>
>>> On Tue, Mar 28, 2023 at 11:39 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
>>>>
>>>> On Sun, Mar 26, 2023 at 01:13:11AM +0300, Arseniy Krasnov wrote:
>>>>> This removes behaviour, where error code returned from any transport
>>>>> was always switched to ENOMEM. This works in the same way as:
>>>>> commit
>>>>> c43170b7e157 ("vsock: return errors other than -ENOMEM to socket"),
>>>>> but for receive calls.
>>>>>
>>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>>>>> ---
>>>>> net/vmw_vsock/af_vsock.c | 4 ++--
>>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>>>>> index 19aea7cba26e..9262e0b77d47 100644
>>>>> --- a/net/vmw_vsock/af_vsock.c
>>>>> +++ b/net/vmw_vsock/af_vsock.c
>>>>> @@ -2007,7 +2007,7 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
>>>>>
>>>>>               read = transport->stream_dequeue(vsk, msg, len - copied, flags);
>>>>
>>>> In vmci_transport_stream_dequeue() vmci_qpair_peekv() and
>>>> vmci_qpair_dequev() return VMCI_ERROR_* in case of errors.
>>>>
>>>> Maybe we should return -ENOMEM in vmci_transport_stream_dequeue() if
>>>> those functions fail to keep the same behavior.
>>
>> Yes, seems i missed it, because several months ago we had similar question for send
>> logic:
>> https://www.spinics.net/lists/kernel/msg4611091.html
>> And it was ok to not handle VMCI send path in this way. So i think current implementation
>> for tx is a little bit buggy, because VMCI specific error from 'vmci_qpair_enquev()' is
>> returned to af_vsock.c. I think error conversion must be added to VMCI transport for tx
>> also.
> 
> Good point!
> 
> These are negative values, so there are no big problems, but I don't
> know what the user expects in this case.
> 
> @Vishnu Do we want to return an errno to the user or a VMCI_ERROR_*?

Small remark, as i can see, VMCI_ERROR_ is not exported to user in include/uapi,
so IIUC user won't be able to interpret such values correctly.

Thanks, Arseniy

> 
> In both cases I think we should do the same for both enqueue and
> dequeue.
> 
>>
>> Good thing is that Hyper-V uses general error codes.
> 
> Yeah!
> 
> Thanks,
> Stefano
> 
>>
>> Thanks, Arseniy
>>>>
>>>> CCing Bryan, Vishnu, and pv-drivers@vmware.com
>>>>
>>>> The other transports seem okay to me.
>>>>
>>>> Thanks,
>>>> Stefano
>>>>
>>>>>               if (read < 0) {
>>>>> -                      err = -ENOMEM;
>>>>> +                      err = read;
>>>>>                       break;
>>>>>               }
>>>>>
>>>>> @@ -2058,7 +2058,7 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
>>>>>       msg_len = transport->seqpacket_dequeue(vsk, msg, flags);
>>>>>
>>>>>       if (msg_len < 0) {
>>>>> -              err = -ENOMEM;
>>>>> +              err = msg_len;
>>>>>               goto out;
>>>>>       }
>>>>>
>>>>> -- 
>>>>> 2.25.1
>>>>>
>>>
>>
>