Subject: Re: [PATCH net] ibmvnic: Allow device probe if the device is not ready at boot

From: Cris Forno <[email-masked]>
Date: Mon, 19 Apr 2021 15:46:39 -0500

Cristobal Forno <[email-masked]> writes:
> This patch will allow the device to be initialized at a later time if
> it is not available at boot. The device will be allowed to probe but
> will be given a "down" state. After completing device probe and
> registering the net device, the driver will await an interrupt signal
> from its partner device, indicating that it is ready for boot. The
> driver will schedule a work event to perform the necessary procedure
> and begin operation.
>
> Signed-off-by: Cristobal Forno <[email-masked]>
> Co-developed-by: Thomas Falcon <[email-masked]>
> ---
>  drivers/net/ethernet/ibm/ibmvnic.c | 145 ++++++++++++++++++++++++-----
>  drivers/net/ethernet/ibm/ibmvnic.h |   6 +-
>  2 files changed, 128 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> index ffb2a91750c7..64798e1f429d 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -141,6 +141,30 @@ static const struct ibmvnic_stat ibmvnic_stats[] = {
>  	{"internal_mac_rx_errors", IBMVNIC_STAT_OFF(internal_mac_rx_errors)},
>  };
>  
> +static int send_crq_init_complete(struct ibmvnic_adapter *adapter)
> +{
> +	union ibmvnic_crq crq;
> +
> +	memset(&crq, 0, sizeof(crq));
> +	crq.generic.first = IBMVNIC_CRQ_INIT_CMD;
> +	crq.generic.cmd = IBMVNIC_CRQ_INIT_COMPLETE;
> +	netdev_dbg(adapter->netdev, "Sending CRQ init complete\n");
> +
> +	return ibmvnic_send_crq(adapter, &crq);
> +}
> +
> +static int send_version_xchg(struct ibmvnic_adapter *adapter)
> +{
> +	union ibmvnic_crq crq;
> +
> +	memset(&crq, 0, sizeof(crq));
> +	crq.version_exchange.first = IBMVNIC_CRQ_CMD;
> +	crq.version_exchange.cmd = VERSION_EXCHANGE;
> +	crq.version_exchange.version = cpu_to_be16(ibmvnic_version);
> +
> +	return ibmvnic_send_crq(adapter, &crq);
> +}
> +
>  static long h_reg_sub_crq(unsigned long unit_address, unsigned long token,
>  			  unsigned long length, unsigned long *number,
>  			  unsigned long *irq)
> @@ -2221,6 +2245,75 @@ static struct ibmvnic_rwi *get_next_rwi(struct ibmvnic_adapter *adapter)
>  	return rwi;
>  }
>  
> +/* ibmvnic_do_passive_init()
> + * Perform the initialization of the device at a later time
> + *
> + * If the ibmvnic was does not have a partner device to communicate with at boot
> + * and that partner device comes online at a later time, this function is called
> + * to complete the initalization process of ibmvnic.
> + * Caller should not hold rtnl_lock().
> + *
> + *
> + * Returns non-zero if sub-CRQs are not initialized properly leaving the device
> + * in the down state.
> + * Returns 0 upon success and the device is probed.
> + */
> +
> +static int do_passive_init(struct ibmvnic_adapter *adapter)
> +{
> +	unsigned long timeout = msecs_to_jiffies(30000);
> +	struct net_device *netdev = adapter->netdev;
> +	struct device *dev = &adapter->vdev->dev;
> +	int rc;
> +
> +	netdev_dbg(adapter->netdev, "Partner device not found, probing.\n");
> +
> +	adapter->state = VNIC_PROBING;
> +	reinit_completion(&adapter->init_done);
> +	adapter->init_done_rc = 0;
> +	adapter->crq.active = true;
> +
> +	rc = send_crq_init_complete(adapter);
> +	if (rc)
> +		goto out;
> +
> +	rc = send_version_xchg(adapter);
> +	netdev_dbg(adapter->netdev, "send_version_xchg rc=%d", rc);
> +
> +	if (!wait_for_completion_timeout(&adapter->init_done, timeout)) {
> +		dev_err(dev, "Initialization sequence timed out\n");
> +		rc = -ETIMEDOUT;
> +		goto out;
> +	}
> +
> +	rc = init_sub_crqs(adapter);
> +	if (rc) {
> +		dev_err(dev, "Initialization of sub crqs failed, rc=%d\n", rc);
> +		goto out;
> +	}
> +
> +	rc = init_sub_crq_irqs(adapter);
> +	if (rc) {
> +		dev_err(dev, "Failed to initialize sub crq irqs\n, rc=%d", rc);
> +		goto init_failed;
> +	}
> +
> +	netdev->mtu = adapter->req_mtu - ETH_HLEN;
> +	netdev->min_mtu = adapter->min_mtu - ETH_HLEN;
> +	netdev->max_mtu = adapter->max_mtu - ETH_HLEN;
> +
> +	adapter->state = VNIC_PROBED;
> +	netdev_dbg(adapter->netdev, "Probed successfully. Waiting for signal from partner device.\n");
> +
> +	return 0;
> +
> +init_failed:
> +	release_sub_crqs(adapter, 1);
> +out:
> +	adapter->state = VNIC_DOWN;
> +	return rc;
> +}
> +
>  static void __ibmvnic_reset(struct work_struct *work)
>  {
>  	struct ibmvnic_rwi *rwi;
> @@ -2256,7 +2349,13 @@ static void __ibmvnic_reset(struct work_struct *work)
>  		}
>  		spin_unlock_irqrestore(&adapter->state_lock, flags);
>  
> -		if (adapter->force_reset_recovery) {
> +		if (rwi->reset_reason == VNIC_RESET_PASSIVE_INIT) {
> +			rtnl_lock();
> +			rc = do_passive_init(adapter);
> +			rtnl_unlock();
> +			if (!rc)
> +				netif_carrier_on(adapter->netdev);
> +		} else if (adapter->force_reset_recovery) {
>  			/* Since we are doing a hard reset now, clear the
>  			 * failover_pending flag so we don't ignore any
>  			 * future MOBILITY or other resets.
> @@ -3724,18 +3823,6 @@ static int ibmvnic_send_crq_init(struct ibmvnic_adapter *adapter)
>  	return 0;
>  }
>  
> -static int send_version_xchg(struct ibmvnic_adapter *adapter)
> -{
> -	union ibmvnic_crq crq;
> -
> -	memset(&crq, 0, sizeof(crq));
> -	crq.version_exchange.first = IBMVNIC_CRQ_CMD;
> -	crq.version_exchange.cmd = VERSION_EXCHANGE;
> -	crq.version_exchange.version = cpu_to_be16(ibmvnic_version);
> -
> -	return ibmvnic_send_crq(adapter, &crq);
> -}
> -
>  struct vnic_login_client_data {
>  	u8	type;
>  	__be16	len;
> @@ -4855,7 +4942,12 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
>  				complete(&adapter->init_done);
>  				adapter->init_done_rc = -EIO;
>  			}
> -			rc = ibmvnic_reset(adapter, VNIC_RESET_FAILOVER);
> +
> +			if (adapter->state == VNIC_DOWN)
> +				rc = ibmvnic_reset(adapter, VNIC_RESET_PASSIVE_INIT);
> +			else
> +				rc = ibmvnic_reset(adapter, VNIC_RESET_FAILOVER);
> +
>  			if (rc && rc != -EBUSY) {
>  				/* We were unable to schedule the failover
>  				 * reset either because the adapter was still
> @@ -5278,6 +5370,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	struct ibmvnic_adapter *adapter;
>  	struct net_device *netdev;
>  	unsigned char *mac_addr_p;
> +	bool init_success;
>  	int rc;
>  
>  	dev_dbg(&dev->dev, "entering ibmvnic_probe for UA 0x%x\n",
> @@ -5324,6 +5417,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	init_completion(&adapter->stats_done);
>  	clear_bit(0, &adapter->resetting);
>  
> +	init_success = false;
>  	do {
>  		rc = init_crq_queue(adapter);
>  		if (rc) {
> @@ -5333,10 +5427,16 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  		}
>  
>  		rc = ibmvnic_reset_init(adapter, false);
> -		if (rc && rc != EAGAIN)
> -			goto ibmvnic_init_fail;
>  	} while (rc == EAGAIN);
>  
> +	/* We are ignoring the error from ibmvnic_reset_init() assuming that the
> +	 * partner is not ready. When the partner becomes ready, we will do the
> +	 * passive init reset.
> +	 */
> +
> +	if (!rc)
> +		init_success = true;
> +
>  	rc = init_stats_buffers(adapter);
>  	if (rc)
>  		goto ibmvnic_init_fail;
> @@ -5345,10 +5445,6 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	if (rc)
>  		goto ibmvnic_stats_fail;
>  
> -	netdev->mtu = adapter->req_mtu - ETH_HLEN;
> -	netdev->min_mtu = adapter->min_mtu - ETH_HLEN;
> -	netdev->max_mtu = adapter->max_mtu - ETH_HLEN;
> -
>  	rc = device_create_file(&dev->dev, &dev_attr_failover);
>  	if (rc)
>  		goto ibmvnic_dev_file_err;
> @@ -5361,7 +5457,14 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  	}
>  	dev_info(&dev->dev, "ibmvnic registered\n");
>  
> -	adapter->state = VNIC_PROBED;
> +	if (init_success) {
> +		adapter->state = VNIC_PROBED;
> +		netdev->mtu = adapter->req_mtu - ETH_HLEN;
> +		netdev->min_mtu = adapter->min_mtu - ETH_HLEN;
> +		netdev->max_mtu = adapter->max_mtu - ETH_HLEN;
> +	} else {
> +		adapter->state = VNIC_DOWN;
> +	}
>  
>  	adapter->wait_for_reset = false;
>  	adapter->last_reset_time = jiffies;
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
> index 806aa75a4e86..98a383e89e44 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.h
> +++ b/drivers/net/ethernet/ibm/ibmvnic.h
> @@ -945,14 +945,16 @@ enum vnic_state {VNIC_PROBING = 1,
>  		 VNIC_CLOSING,
>  		 VNIC_CLOSED,
>  		 VNIC_REMOVING,
> -		 VNIC_REMOVED};
> +		 VNIC_REMOVED,
> +		 VNIC_DOWN};
>  
>  enum ibmvnic_reset_reason {VNIC_RESET_FAILOVER = 1,
>  			   VNIC_RESET_MOBILITY,
>  			   VNIC_RESET_FATAL,
>  			   VNIC_RESET_NON_FATAL,
>  			   VNIC_RESET_TIMEOUT,
> -			   VNIC_RESET_CHANGE_PARAM};
> +			   VNIC_RESET_CHANGE_PARAM,
> +			   VNIC_RESET_PASSIVE_INIT};
>  
>  struct ibmvnic_rwi {
>  	enum ibmvnic_reset_reason reset_reason;
> -- 
> 2.30.0

Hi all,

Few things I failed to add to this patch:

1. Correctly format the Co-developed-by tag
2. CC all the maintainers
3. This patch doesn't fix a bug in a specific commit, therefore
I have to submit this to net-next.

I will submit a v2 shortly.

Best,
Cris Forno