Re: [PATCH net 1/2] iavf: Fix error when changing ring parameters on ice PF

[Jakub Kicinski <kuba@kernel.org>]

On Wed, 20 Apr 2022 10:26:23 -0700 Tony Nguyen wrote:
> From: Michal Maloszewski <michal.maloszewski@intel.com>
> 
> Reset is triggered when ring parameters are being changed through
> ethtool and queues are reconfigured for VF's VSI. If ring is changed
> again immediately, then the next reset could be executed before
> queues could be properly reinitialized on VF's VSI. It caused ice PF
> to mess up the VSI resource tree.
> 
> Add a check in iavf_set_ringparam for adapter and VF's queue
> state. If VF is currently resetting or queues are disabled for the VF
> return with EAGAIN error.

Can't we wait for the device to get into the right state?
Throwing EAGAIN back to user space is not very friendly.

> diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> index 3bb56714beb0..08efbc50fbe9 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> @@ -631,6 +631,11 @@ static int iavf_set_ringparam(struct net_device *netdev,
>  	if ((ring->rx_mini_pending) || (ring->rx_jumbo_pending))
>  		return -EINVAL;
>  
> +	if (adapter->state == __IAVF_RESETTING ||
> +	    (adapter->state == __IAVF_RUNNING &&
> +	     (adapter->flags & IAVF_FLAG_QUEUES_DISABLED)))
> +		return -EAGAIN;

nit: why add this check in the middle of input validation 
(i.e. checking the ring params are supported)?

>  	if (ring->tx_pending > IAVF_MAX_TXD ||
>  	    ring->tx_pending < IAVF_MIN_TXD ||
>  	    ring->rx_pending > IAVF_MAX_RXD ||