Messages in this thread | | | From | Haiyang Zhang <> | Subject | RE: [PATCH V3,net-next, 1/2] hv_netvsc: Add XDP support | Date | Thu, 23 Jan 2020 17:44:52 +0000 |
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> -----Original Message----- > From: Jakub Kicinski <kuba@kernel.org> > Sent: Thursday, January 23, 2020 12:30 PM > To: Haiyang Zhang <haiyangz@microsoft.com> > Cc: sashal@kernel.org; linux-hyperv@vger.kernel.org; netdev@vger.kernel.org; > KY Srinivasan <kys@microsoft.com>; Stephen Hemminger > <sthemmin@microsoft.com>; olaf@aepfle.de; vkuznets > <vkuznets@redhat.com>; davem@davemloft.net; linux-kernel@vger.kernel.org > Subject: Re: [PATCH V3,net-next, 1/2] hv_netvsc: Add XDP support > > On Thu, 23 Jan 2020 17:14:06 +0000, Haiyang Zhang wrote: > > > > Changes: > > > > v3: Minor code and comment updates. > > > > v2: Added XDP_TX support. Addressed review comments. > > > > > > How does the locking of the TX path work? You seem to be just > > > calling the normal xmit method, but you don't hold the xmit queue > > > lock, so the stack can start xmit concurrently, no? > > > > The netvsc and vmbus can handle concurrent transmits, except the msd > > (Multi-Send Data) field which can only be used by one queue. > > > > I already added a new flag to netvsc_send(), so packets from XDP_TX > > won't use the msd. > > I see, there's a few non-atomic counters there, but maybe that's not a big deal. Yes, those error counters are used less frequently, and not necessary to be precise.
> What frees the skb if the ring is full, and netvsc_send_pkt() returns -EAGAIN? > Nothing checks the return value from netvsc_xdp_xmit(). Good catch! I will add skb free when -EAGAIN is returned for XDP_TX. I will update the patch.
Thanks, - Haiyang
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