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SubjectRE: [PATCH net] hyperv: Fix the error processing in netvsc_send()


On Fri, Jan 30, 2015 at 11:05 PM, Haiyang Zhang
<haiyangz@microsoft.com> wrote:
>
>
>> -----Original Message-----
>> From: Jason Wang [mailto:jasowang@redhat.com]
>> Sent: Friday, January 30, 2015 5:25 AM
>> > + if (ret != 0) {
>> > + if (section_index != NETVSC_INVALID_INDEX)
>> > + netvsc_free_send_slot(net_device, section_index);
>>
>> What if ret is -EINVAL or -ENOSPC? Looks like we need free the skb
>> in
>> this case also.
>
> In these cases, skb is freed in netvsc_start_xmit().
>
>
>> >
>> > + } else if (skb) {
>> > + dev_kfree_skb_any(skb);
>>
>> The caller - netvsc_start_xmit() do this also, may be handle this in
>> caller is better since netvsc_start_xmit() is the only user that
>> tries
>> to send a skb?
>
> When the packet is sent out normally, we frees it in netvsc_send() if
> it's
> copied to send-buffer. The free is done in netvsc_send(), because the
> copy
> is also in this function. If it's not copied, it will be freed in
> another
> function -- netvsc_xmit_completion().
>
> netvsc_start_xmit() only does free skb in error case.

Ok.
>
>
>> btw, I find during netvsc_start_xmit(), ret was change to -ENOSPC
>> when
>> queue_sends[q_idx] < 1. But non of the caller check -ENOSPC in fact?
>
> In this case, we don't request re-send, so set ret to a value other
> than
> -EAGAIN.

Why not? We have available slots for it to be sent now. Dropping the
packet in this case may cause out of order sending.
> It's handled in the same way as errors != -EAGAIN, so we don't
> need to check this value specifically.

Thanks



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