Re: [PATCH v2 net] net: mana: Fix doorbell out of order violation and avoid unnecessary doorbell rings

[Simon Horman]

On Wed, Aug 07, 2024 at 04:17:06PM -0700, longli@xxxxxxxxxxxxxxxxx wrote:
> From: Long Li <longli@xxxxxxxxxxxxx>
> 
> After napi_complete_done() is called when NAPI is polling in the current
> process context, another NAPI may be scheduled and start running in
> softirq on another CPU and may ring the doorbell before the current CPU
> does. When combined with unnecessary rings when there is no need to arm
> the CQ, it triggers error paths in the hardware.
> 
> This patch fixes this by calling napi_complete_done() after doorbell
> rings. It limits the number of unnecessary rings when there is
> no need to arm. MANA hardware specifies that there must be one doorbell
> ring every 8 CQ wraparounds. This driver guarantees one doorbell ring as
> soon as the number of consumed CQEs exceeds 4 CQ wraparounds. In pratical

nit: practical

     Flagged by checkpatch.pl --codespell

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