linux-kernel - Re: [PATCH V2 net] net: mana: Fix MANA VF unload when host is unresponsive

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Message-ID: <ZJXZ8mg5uw8MaKuP@corigine.com>
Date:   Fri, 23 Jun 2023 19:44:18 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     souradeep chakrabarti <schakrabarti@...ux.microsoft.com>
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, longli@...rosoft.com,
        sharmaajay@...rosoft.com, leon@...nel.org, cai.huoqing@...ux.dev,
        ssengar@...ux.microsoft.com, vkuznets@...hat.com,
        tglx@...utronix.de, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, stable@...r.kernel.org,
        schakrabarti@...rosoft.com
Subject: Re: [PATCH V2 net] net: mana: Fix MANA VF unload when host is
 unresponsive

On Fri, Jun 23, 2023 at 12:29:15AM -0700, souradeep chakrabarti wrote:
> From: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>
> 
> This patch addresses  the VF unload issue, where mana_dealloc_queues()
> gets stuck in infinite while loop, because of host unresponsiveness.
> It adds a timeout in the while loop, to fix it.
> 
> Also this patch adds a new attribute in mana_context, which gets set when
> mana_hwc_send_request() hits a timeout because of host unresponsiveness.
> This flag then helps to avoid the timeouts in successive calls.
> 
> Signed-off-by: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>

...

> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index d907727c7b7a..cb2080b3a00c 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c

...

> @@ -2348,13 +2351,26 @@ static int mana_dealloc_queues(struct net_device *ndev)
>  	 *
>  	 * Drain all the in-flight TX packets
>  	 */
> +
> +	timeout = jiffies + 120 * HZ;
>  	for (i = 0; i < apc->num_queues; i++) {
>  		txq = &apc->tx_qp[i].txq;
> -
> -		while (atomic_read(&txq->pending_sends) > 0)
> +		while (atomic_read(&txq->pending_sends) > 0 &&
> +		       time_before(jiffies, timeout)) {
>  			usleep_range(1000, 2000);
> +		}

Hi Souradeep,

minor feedback from my side, as it seems there will be a new version anyway:
I think the braces - '{' '}' - are unnecessary above.

...

-- 
pw-bot: cr