netdev - Re: [net PATCH] hv_netvsc: Fix unwanted wakeup in netvsc

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Date:   Sun, 23 Feb 2020 16:33:02 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     haiyangz@...rosoft.com
Cc:     sashal@...nel.org, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, kys@...rosoft.com, sthemmin@...rosoft.com,
        olaf@...fle.de, vkuznets@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [net PATCH] hv_netvsc: Fix unwanted wakeup in netvsc_attach()

From: Haiyang Zhang <haiyangz@...rosoft.com>
Date: Fri, 21 Feb 2020 08:32:18 -0800

> When netvsc_attach() is called by operations like changing MTU, etc.,
> an extra wakeup may happen while netvsc_attach() calling
> rndis_filter_device_add() which sends rndis messages when queue is
> stopped in netvsc_detach(). The completion message will wake up queue 0.
> 
> We can reproduce the issue by changing MTU etc., then the wake_queue
> counter from "ethtool -S" will increase beyond stop_queue counter:
>      stop_queue: 0
>      wake_queue: 1
> The issue causes queue wake up, and counter increment, no other ill
> effects in current code. So we didn't see any network problem for now.
> 
> To fix this, initialize tx_disable to true, and set it to false when
> the NIC is ready to be attached or registered.
> 
> Fixes: 7b2ee50c0cd5 ("hv_netvsc: common detach logic")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>

Applied, thank you.