netdev - Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi

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Date:   Tue, 13 Apr 2021 00:24:35 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     weiwan@...gle.com, netdev@...r.kernel.org, kuba@...nel.org,
        willemb@...gle.com, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi

On Mon, Apr 12, 2021 at 04:14:58PM -0700, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@...hat.com>
> Date: Mon, 12 Apr 2021 18:33:45 -0400
> 
> > On Mon, Apr 12, 2021 at 06:08:21PM -0400, Michael S. Tsirkin wrote:
> >> OK I started looking at this again. My idea is simple.
> >> A. disable callbacks before we try to drain skbs
> >> B. actually do disable callbacks even with event idx
> >> 
> >> To make B not regress, we need to
> >> C. detect the common case of disable after event triggering and skip the write then.
> >> 
> >> I added a new event_triggered flag for that.
> >> Completely untested - but then I could not see the warnings either.
> >> Would be very much interested to know whether this patch helps
> >> resolve the sruprious interrupt problem at all ...
> >> 
> >> 
> >> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> > 
> > Hmm a slightly cleaner alternative is to clear the flag when enabling interrupts ...
> > I wonder which cacheline it's best to use for this.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> 
> Please make a fresh new submission if you want to use this approach, thanks.

Absolutely. This is untested so I just sent this idea out for early feedback
and hopefully help with testing on real hardware.
Sorry about being unclear.

-- 
MST