netdev - Re: [PATCH V2 net] ibmvnic: Continue with reset if set link down failed

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Date:   Tue, 20 Apr 2021 16:42:24 -0500
From:   Lijun Pan <ljp@...ux.vnet.ibm.com>
To:     Dany Madden <drt@...ux.ibm.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Tom Falcon <tlfalcon@...ux.ibm.com>, netdev@...r.kernel.org,
        paulus@...ba.org, Sukadev Bhattiprolu <sukadev@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH V2 net] ibmvnic: Continue with reset if set link down
 failed



> On Apr 20, 2021, at 4:35 PM, Dany Madden <drt@...ux.ibm.com> wrote:
> 
> When ibmvnic gets a FATAL error message from the vnicserver, it marks
> the Command Respond Queue (CRQ) inactive and resets the adapter. If this
> FATAL reset fails and a transmission timeout reset follows, the CRQ is
> still inactive, ibmvnic's attempt to set link down will also fail. If
> ibmvnic abandons the reset because of this failed set link down and this
> is the last reset in the workqueue, then this adapter will be left in an
> inoperable state.
> 
> Instead, make the driver ignore this link down failure and continue to
> free and re-register CRQ so that the adapter has an opportunity to
> recover.

This v2 does not adddress the concerns mentioned in v1.
And I think it is better to exit with error from do_reset, and schedule a thorough
do_hard_reset if the the adapter is already in unstable state.

> 
> Fixes: ed651a10875f ("ibmvnic: Updated reset handling")
> Signed-off-by: Dany Madden <drt@...ux.ibm.com>
> Reviewed-by: Rick Lindsley <ricklind@...ux.ibm.com>
> Reviewed-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
> ---
> Changes in V2:
> - Update description to clarify background for the patch
> - Include Reviewed-by tags
> ---
> drivers/net/ethernet/ibm/ibmvnic.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> index ffb2a91750c7..4bd8c5d1a275 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -1970,8 +1970,10 @@ static int do_reset(struct ibmvnic_adapter *adapter,
> 			rtnl_unlock();
> 			rc = set_link_state(adapter, IBMVNIC_LOGICAL_LNK_DN);
> 			rtnl_lock();
> -			if (rc)
> -				goto out;
> +			if (rc) {
> +				netdev_dbg(netdev,
> +					   "Setting link down failed rc=%d. Continue anyway\n", rc);
> +			}
> 
> 			if (adapter->state == VNIC_OPEN) {
> 				/* When we dropped rtnl, ibmvnic_open() got
> -- 
> 2.26.2
>