netdev - Re: [PATCH net 3/3] ibmvnic: delay complete()

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Date:   Fri, 29 Oct 2021 15:25:27 -0700
From:   Dany Madden <drt@...ux.ibm.com>
To:     Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
Cc:     netdev@...r.kernel.org, Brian King <brking@...ux.ibm.com>,
        abdhalee@...ibm.com, vaish123@...ibm.com
Subject: Re: [PATCH net 3/3] ibmvnic: delay complete()

On 2021-10-29 15:03, Sukadev Bhattiprolu wrote:
> If we get CRQ_INIT, we set errno to -EIO and first call complete() to
> notify the waiter. Then we try to schedule a FAILOVER reset. If this
> occurs while adapter is in PROBING state, ibmvnic_reset() changes the
> error code to EAGAIN and returns without scheduling the FAILOVER. The
> purpose of setting error code to EAGAIN is to ask the waiter to retry.
> 
> But due to the earlier complete() call, the waiter may already have 
> seen
> the -EIO response and decided not to retry. This can cause intermittent
> failures when bringing up ibmvnic adapters during boot, specially in
> in kexec/kdump kernels.
> 
> Defer the complete() call until after scheduling the reset.
> 
> Also streamline the error code to EAGAIN. Don't see why we need EIO
> sometimes. All 3 callers of ibmvnic_reset_init() can handle EAGAIN.
> 
> Fixes: 17c8705838a5 ("ibmvnic: Return error code if init interrupted
> by transport event")
> Reported-by: Vaishnavi Bhat <vaish123@...ibm.com>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>

Reviewed-by: Dany Madden <drt@...ux.ibm.com>

> ---
>  drivers/net/ethernet/ibm/ibmvnic.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c
> b/drivers/net/ethernet/ibm/ibmvnic.c
> index 50956f622b11..29cbf60dfd79 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -2755,7 +2755,7 @@ static int ibmvnic_reset(struct ibmvnic_adapter 
> *adapter,
> 
>  	if (adapter->state == VNIC_PROBING) {
>  		netdev_warn(netdev, "Adapter reset during probe\n");
> -		adapter->init_done_rc = EAGAIN;
> +		adapter->init_done_rc = -EAGAIN;
>  		ret = EAGAIN;
>  		goto err;
>  	}
> @@ -5266,11 +5266,6 @@ static void ibmvnic_handle_crq(union ibmvnic_crq 
> *crq,
>  			 */
>  			adapter->login_pending = false;
> 
> -			if (!completion_done(&adapter->init_done)) {
> -				complete(&adapter->init_done);
> -				adapter->init_done_rc = -EIO;
> -			}
> -
>  			if (adapter->state == VNIC_DOWN)
>  				rc = ibmvnic_reset(adapter, VNIC_RESET_PASSIVE_INIT);
>  			else
> @@ -5291,6 +5286,13 @@ static void ibmvnic_handle_crq(union ibmvnic_crq 
> *crq,
>  					   rc);
>  				adapter->failover_pending = false;
>  			}
> +
> +			if (!completion_done(&adapter->init_done)) {
> +				complete(&adapter->init_done);
> +				if (!adapter->init_done_rc)
> +					adapter->init_done_rc = -EAGAIN;
> +			}
> +
>  			break;
>  		case IBMVNIC_CRQ_INIT_COMPLETE:
>  			dev_info(dev, "Partner initialization complete\n");
> @@ -5763,7 +5765,7 @@ static int ibmvnic_probe(struct vio_dev *dev,
> const struct vio_device_id *id)
>  		}
> 
>  		rc = ibmvnic_reset_init(adapter, false);
> -	} while (rc == EAGAIN);
> +	} while (rc == -EAGAIN);
> 
>  	/* We are ignoring the error from ibmvnic_reset_init() assuming that 
> the
>  	 * partner is not ready. CRQ is not active. When the partner becomes