Re: [PATCH v2 net] net: mana: Fix doorbell out of order violation and avoid unnecessary doorbell rings
From: Simon Horman <horms@kernel.org>
Date: 2024-08-09 08:47:22
Also in:
linux-hyperv, linux-rdma, lkml, stable
On Wed, Aug 07, 2024 at 04:17:06PM -0700, longli@linuxonhyperv.com wrote:
From: Long Li <longli@microsoft.com> 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
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