netdev - Re: [PATCH net] net/mlx4_core: Avoid command timeouts during VF driver device shutdown

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Date:   Mon, 30 Jan 2017 15:45:40 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     tariqt@...lanox.com
Cc:     netdev@...r.kernel.org, eranbe@...lanox.com,
        jackm@....mellanox.co.il
Subject: Re: [PATCH net] net/mlx4_core: Avoid command timeouts during VF
 driver device shutdown

From: Tariq Toukan <tariqt@...lanox.com>
Date: Mon, 30 Jan 2017 15:11:45 +0200

> From: Jack Morgenstein <jackm@....mellanox.co.il>
> 
> Some Hypervisors detach VFs from VMs by instantly causing an FLR event
> to be generated for a VF.
> 
> In the mlx4 case, this will cause that VF's comm channel to be disabled
> before the VM has an opportunity to invoke the VF device's "shutdown"
> method.
> 
> The result is that the VF driver on the VM will experience a command
> timeout during the shutdown process when the Hypervisor does not deliver
> a command-completion event to the VM.
> 
> To avoid FW command timeouts on the VM when the driver's shutdown method
> is invoked, we detect the absence of the VF's comm channel at the very
> start of the shutdown process. If the comm-channel has already been
> disabled, we cause all FW commands during the device shutdown process to
> immediately return success (and thus avoid all command timeouts).
> 
> Signed-off-by: Jack Morgenstein <jackm@....mellanox.co.il>
> Signed-off-by: Tariq Toukan <tariqt@...lanox.com>

Applied, thanks.