fm10k: introduce a message queue for MAC/VLAN messages

Under some circumstances, when dealing with a large number of MAC
address or VLAN updates at once, the fm10k driver, particularly the VFs
can overload the mailbox with too many messages at once.

This results in a mailbox timeout, which causes the driver to initiate
a reset. During the reset, we re-send all the same messages that
originally caused the timeout. This results in a cycle of resets each
triggering a future reset.

To fix or avoid this, we introduce a workqueue item which monitors
a queue of MAC and VLAN requests. These requests are queued to the end
of the list, and we process as a FIFO periodically.

Initially we only handle requests for the netdev, but we do handle
unicast MAC addresses, multicast MAC addresses, and update VLAN
requests.

A future patch will add support to use this queue for handling MAC
update requests from the VF<->PF mailbox.

The MAC/VLAN work item will keep checking to make sure that each request
does not overflow the mailbox and cause a timeout. If it might, then the
work item will reschedule itself a short time later. This avoids any
reset cycle, since we never send the message if the mailbox is not
ready.

As an alternative, we tried increasing the mailbox message FIFO, but
this just delays the problem and results in needless memory waste on the
system. Our new message queue is dynamically allocated so only uses as
much memory as it needs. Additionally, it need not be contiguous like
the Tx and Rx FIFOs.

Note that this patch chose to only create a queue for MAC and VLAN
messages, since these are the only messages sent in a large enough
volume to cause the reset loop. Other messages are very unlikely to
overflow the mailbox Tx FIFO so easily.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 201 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
index aef39909e4a2..58538ce997e1 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
@@ -91,6 +91,76 @@ static int fm10k_hw_ready(struct fm10k_intfc *interface)
 	return FM10K_REMOVED(hw->hw_addr) ? -ENODEV : 0;
 }
 
+/**
+ * fm10k_macvlan_schedule - Schedule MAC/VLAN queue task
+ * @interface: fm10k private interface structure
+ *
+ * Schedule the MAC/VLAN queue monitor task. If the MAC/VLAN task cannot be
+ * started immediately, request that it be restarted when possible.
+ */
+void fm10k_macvlan_schedule(struct fm10k_intfc *interface)
+{
+	/* Avoid processing the MAC/VLAN queue when the service task is
+	 * disabled, or when we're resetting the device.
+	 */
+	if (!test_bit(__FM10K_MACVLAN_DISABLE, interface->state) &&
+	    !test_and_set_bit(__FM10K_MACVLAN_SCHED, interface->state)) {
+		clear_bit(__FM10K_MACVLAN_REQUEST, interface->state);
+		/* We delay the actual start of execution in order to allow
+		 * multiple MAC/VLAN updates to accumulate before handling
+		 * them, and to allow some time to let the mailbox drain
+		 * between runs.
+		 */
+		queue_delayed_work(fm10k_workqueue,
+				   &interface->macvlan_task, 10);
+	} else {
+		set_bit(__FM10K_MACVLAN_REQUEST, interface->state);
+	}
+}
+
+/**
+ * fm10k_stop_macvlan_task - Stop the MAC/VLAN queue monitor
+ * @interface: fm10k private interface structure
+ *
+ * Wait until the MAC/VLAN queue task has stopped, and cancel any future
+ * requests.
+ */
+static void fm10k_stop_macvlan_task(struct fm10k_intfc *interface)
+{
+	/* Disable the MAC/VLAN work item */
+	set_bit(__FM10K_MACVLAN_DISABLE, interface->state);
+
+	/* Make sure we waited until any current invocations have stopped */
+	cancel_delayed_work_sync(&interface->macvlan_task);
+
+	/* We set the __FM10K_MACVLAN_SCHED bit when we schedule the task.
+	 * However, it may not be unset of the MAC/VLAN task never actually
+	 * got a chance to run. Since we've canceled the task here, and it
+	 * cannot be rescheuled right now, we need to ensure the scheduled bit
+	 * gets unset.
+	 */
+	clear_bit(__FM10K_MACVLAN_SCHED, interface->state);
+}
+
+/**
+ * fm10k_resume_macvlan_task - Restart the MAC/VLAN queue monitor
+ * @interface: fm10k private interface structure
+ *
+ * Clear the __FM10K_MACVLAN_DISABLE bit and, if a request occurred, schedule
+ * the MAC/VLAN work monitor.
+ */
+static void fm10k_resume_macvlan_task(struct fm10k_intfc *interface)
+{
+	/* Re-enable the MAC/VLAN work item */
+	clear_bit(__FM10K_MACVLAN_DISABLE, interface->state);
+
+	/* We might have received a MAC/VLAN request while disabled. If so,
+	 * kick off the queue now.
+	 */
+	if (test_bit(__FM10K_MACVLAN_REQUEST, interface->state))
+		fm10k_macvlan_schedule(interface);
+}
+
 void fm10k_service_event_schedule(struct fm10k_intfc *interface)
 {
 	if (!test_bit(__FM10K_SERVICE_DISABLE, interface->state) &&
@@ -174,6 +244,12 @@ static bool fm10k_prepare_for_reset(struct fm10k_intfc *interface)
 	if (test_and_set_bit(__FM10K_RESETTING, interface->state))
 		return false;
 
+	/* As the MAC/VLAN task will be accessing registers it must not be
+	 * running while we reset. Although the task will not be scheduled
+	 * once we start resetting it may already be running
+	 */
+	fm10k_stop_macvlan_task(interface);
+
 	rtnl_lock();
 
 	fm10k_iov_suspend(interface->pdev);
@@ -258,6 +334,8 @@ static int fm10k_handle_reset(struct fm10k_intfc *interface)
 
 	rtnl_unlock();
 
+	fm10k_resume_macvlan_task(interface);
+
 	clear_bit(__FM10K_RESETTING, interface->state);
 
 	return err;
@@ -687,6 +765,112 @@ static void fm10k_service_task(struct work_struct *work)
 }
 
 /**
+ * fm10k_macvlan_task - send queued MAC/VLAN requests to switch manager
+ * @work: pointer to work_struct containing our data
+ *
+ * This work item handles sending MAC/VLAN updates to the switch manager. When
+ * the interface is up, it will attempt to queue mailbox messages to the
+ * switch manager requesting updates for MAC/VLAN pairs. If the Tx fifo of the
+ * mailbox is full, it will reschedule itself to try again in a short while.
+ * This ensures that the driver does not overload the switch mailbox with too
+ * many simultaneous requests, causing an unnecessary reset.
+ **/
+static void fm10k_macvlan_task(struct work_struct *work)
+{
+	struct fm10k_macvlan_request *item;
+	struct fm10k_intfc *interface;
+	struct delayed_work *dwork;
+	struct list_head *requests;
+	struct fm10k_hw *hw;
+	unsigned long flags;
+
+	dwork = to_delayed_work(work);
+	interface = container_of(dwork, struct fm10k_intfc, macvlan_task);
+	hw = &interface->hw;
+	requests = &interface->macvlan_requests;
+
+	do {
+		/* Pop the first item off the list */
+		spin_lock_irqsave(&interface->macvlan_lock, flags);
+		item = list_first_entry_or_null(requests,
+						struct fm10k_macvlan_request,
+						list);
+		if (item)
+			list_del_init(&item->list);
+
+		spin_unlock_irqrestore(&interface->macvlan_lock, flags);
+
+		/* We have no more items to process */
+		if (!item)
+			goto done;
+
+		fm10k_mbx_lock(interface);
+
+		/* Check that we have plenty of space to send the message. We
+		 * want to ensure that the mailbox stays low enough to avoid a
+		 * change in the host state, otherwise we may see spurious
+		 * link up / link down notifications.
+		 */
+		if (!hw->mbx.ops.tx_ready(&hw->mbx, FM10K_VFMBX_MSG_MTU + 5)) {
+			hw->mbx.ops.process(hw, &hw->mbx);
+			set_bit(__FM10K_MACVLAN_REQUEST, interface->state);
+			fm10k_mbx_unlock(interface);
+
+			/* Put the request back on the list */
+			spin_lock_irqsave(&interface->macvlan_lock, flags);
+			list_add(&item->list, requests);
+			spin_unlock_irqrestore(&interface->macvlan_lock, flags);
+			break;
+		}
+
+		switch (item->type) {
+		case FM10K_MC_MAC_REQUEST:
+			hw->mac.ops.update_mc_addr(hw,
+						   item->mac.glort,
+						   item->mac.addr,
+						   item->mac.vid,
+						   item->set);
+			break;
+		case FM10K_UC_MAC_REQUEST:
+			hw->mac.ops.update_uc_addr(hw,
+						   item->mac.glort,
+						   item->mac.addr,
+						   item->mac.vid,
+						   item->set,
+						   0);
+			break;
+		case FM10K_VLAN_REQUEST:
+			hw->mac.ops.update_vlan(hw,
+						item->vlan.vid,
+						item->vlan.vsi,
+						item->set);
+			break;
+		default:
+			break;
+		}
+
+		fm10k_mbx_unlock(interface);
+
+		/* Free the item now that we've sent the update */
+		kfree(item);
+	} while (true);
+
+done:
+	WARN_ON(!test_bit(__FM10K_MACVLAN_SCHED, interface->state));
+
+	/* flush memory to make sure state is correct */
+	smp_mb__before_atomic();
+	clear_bit(__FM10K_MACVLAN_SCHED, interface->state);
+
+	/* If a MAC/VLAN request was scheduled since we started, we should
+	 * re-schedule. However, there is no reason to re-schedule if there is
+	 * no work to do.
+	 */
+	if (test_bit(__FM10K_MACVLAN_REQUEST, interface->state))
+		fm10k_macvlan_schedule(interface);
+}
+
+/**
  * fm10k_configure_tx_ring - Configure Tx ring after Reset
  * @interface: board private structure
  * @ring: structure containing ring specific data
@@ -1918,11 +2102,15 @@ static int fm10k_sw_init(struct fm10k_intfc *interface,
 	INIT_LIST_HEAD(&interface->vxlan_port);
 	INIT_LIST_HEAD(&interface->geneve_port);
 
+	/* Initialize the MAC/VLAN queue */
+	INIT_LIST_HEAD(&interface->macvlan_requests);
+
 	netdev_rss_key_fill(rss_key, sizeof(rss_key));
 	memcpy(interface->rssrk, rss_key, sizeof(rss_key));
 
 	/* Initialize the mailbox lock */
 	spin_lock_init(&interface->mbx_lock);
+	spin_lock_init(&interface->macvlan_lock);
 
 	/* Start off interface as being down */
 	set_bit(__FM10K_DOWN, interface->state);
@@ -2131,6 +2319,9 @@ static int fm10k_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		    (unsigned long)interface);
 	INIT_WORK(&interface->service_task, fm10k_service_task);
 
+	/* Setup the MAC/VLAN queue */
+	INIT_DELAYED_WORK(&interface->macvlan_task, fm10k_macvlan_task);
+
 	/* kick off service timer now, even when interface is down */
 	mod_timer(&interface->service_timer, (HZ * 2) + jiffies);
 
@@ -2184,6 +2375,10 @@ static void fm10k_remove(struct pci_dev *pdev)
 	del_timer_sync(&interface->service_timer);
 
 	fm10k_stop_service_event(interface);
+	fm10k_stop_macvlan_task(interface);
+
+	/* Remove all pending MAC/VLAN requests */
+	fm10k_clear_macvlan_queue(interface, interface->glort, true);
 
 	/* free netdev, this may bounce the interrupts due to setup_tc */
 	if (netdev->reg_state == NETREG_REGISTERED)
@@ -2220,6 +2415,9 @@ static void fm10k_prepare_suspend(struct fm10k_intfc *interface)
 	 * a surprise remove if the PCIe device is disabled while we're
 	 * stopped. We stop the watchdog task until after we resume software
 	 * activity.
+	 *
+	 * Note that the MAC/VLAN task will be stopped as part of preparing
+	 * for reset so we don't need to handle it here.
 	 */
 	fm10k_stop_service_event(interface);
 
@@ -2259,6 +2457,9 @@ static int fm10k_handle_resume(struct fm10k_intfc *interface)
 	/* restart the service task */
 	fm10k_start_service_event(interface);
 
+	/* Restart the MAC/VLAN request queue in-case of outstanding events */
+	fm10k_macvlan_schedule(interface);
+
 	return err;
 }