linux-kernel - Re: [PATCH v2 net] net: fix premature exit from NAPI state polling in napi

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Date:   Thu, 11 Nov 2021 02:00:07 +0000
From:   patchwork-bot+netdevbpf@...nel.org
To:     Alexander Lobakin <alexandr.lobakin@...el.com>
Cc:     davem@...emloft.net, kuba@...nel.org, jesse.brandeburg@...el.com,
        maciej.fijalkowski@...el.com, michal.swiatkowski@...el.com,
        xuanzhuo@...ux.alibaba.com, atenart@...nel.org,
        edumazet@...gle.com, weiwan@...gle.com, bjorn@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net] net: fix premature exit from NAPI state polling in
 napi_disable()

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@...nel.org>:

On Wed, 10 Nov 2021 20:56:05 +0100 you wrote:
> Commit 719c57197010 ("net: make napi_disable() symmetric with
> enable") accidentally introduced a bug sometimes leading to a kernel
> BUG when bringing an iface up/down under heavy traffic load.
> 
> Prior to this commit, napi_disable() was polling n->state until
> none of (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC) is set and then
> always flip them. Now there's a possibility to get away with the
> NAPIF_STATE_SCHE unset as 'continue' drops us to the cmpxchg()
> call with an unitialized variable, rather than straight to
> another round of the state check.
> 
> [...]

Here is the summary with links:
  - [v2,net] net: fix premature exit from NAPI state polling in napi_disable()
    https://git.kernel.org/netdev/net/c/0315a075f134

You are awesome, thank you!
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