i40e: initialize our affinity_mask based on cpu_possible_mask

On older kernels a call to irq_set_affinity_hint does not guarantee that
the IRQ affinity will be set. If nothing else on the system sets the IRQ
affinity this can result in a bug in the i40e_napi_poll() routine where
we notice that our interrupt fired on the "wrong" CPU according to our
internal affinity_mask variable.

This results in a bug where we continuously tell NAPI to stop polling to
move the interrupt to a new CPU, but the CPU never changes because our
affinity mask does not match the actual mask setup for the IRQ.

The root problem is a mismatched affinity mask value. So lets initialize
the value to cpu_possible_mask instead. This ensures that prior to the
first time we get an IRQ affinity notification we'll have the mask set
to include every possible CPU.

We use cpu_possible_mask instead of cpu_online_mask since the former is
almost certainly never going to change, while the later might change
after we've made a copy.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 7366e7c..6498da8 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -2881,7 +2881,7 @@ static void i40e_config_xps_tx_ring(struct i40e_ring *ring)
        if ((vsi->tc_config.numtc <= 1) &&
            !test_and_set_bit(__I40E_TX_XPS_INIT_DONE, &ring->state)) {
                netif_set_xps_queue(ring->netdev,
-                                   &ring->q_vector->affinity_mask,
+                                   get_cpu_mask(ring->q_vector->v_idx),
                                    ring->queue_index);
        }
 
@@ -3506,8 +3506,10 @@ static int i40e_vsi_request_irq_msix(struct i40e_vsi *vsi, char *basename)
                q_vector->affinity_notify.notify = i40e_irq_affinity_notify;
                q_vector->affinity_notify.release = i40e_irq_affinity_release;
                irq_set_affinity_notifier(irq_num, &q_vector->affinity_notify);
-               /* assign the mask for this irq */
-               irq_set_affinity_hint(irq_num, &q_vector->affinity_mask);
+               /* get_cpu_mask returns a static constant mask with
+                * a permanent lifetime so it's ok to use here.
+                */
+               irq_set_affinity_hint(irq_num, get_cpu_mask(q_vector->v_idx));
        }
 
        vsi->irqs_ready = true;
@@ -4289,7 +4291,7 @@ static void i40e_vsi_free_irq(struct i40e_vsi *vsi)
 
                        /* clear the affinity notifier in the IRQ descriptor */
                        irq_set_affinity_notifier(irq_num, NULL);
-                       /* clear the affinity_mask in the IRQ descriptor */
+                       /* remove our suggested affinity mask for this IRQ */
                        irq_set_affinity_hint(irq_num, NULL);
                        synchronize_irq(irq_num);
                        free_irq(irq_num, vsi->q_vectors[i]);
@@ -8235,7 +8237,7 @@ static int i40e_vsi_alloc_q_vector(struct i40e_vsi *vsi, int v_idx, int cpu)
 
        q_vector->vsi = vsi;
        q_vector->v_idx = v_idx;
-       cpumask_set_cpu(cpu, &q_vector->affinity_mask);
+       cpumask_copy(&q_vector->affinity_mask, cpu_possible_mask);
 
        if (vsi->netdev)
                netif_napi_add(vsi->netdev, &q_vector->napi,

diff --git a/drivers/net/ethernet/intel/i40evf/i40evf_main.c b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
index 9ee277e..1825d95 100644 (file)
--- a/drivers/net/ethernet/intel/i40evf/i40evf_main.c
+++ b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
@@ -584,8 +584,10 @@ i40evf_request_traffic_irqs(struct i40evf_adapter *adapter, char *basename)
                q_vector->affinity_notify.release =
                                                   i40evf_irq_affinity_release;
                irq_set_affinity_notifier(irq_num, &q_vector->affinity_notify);
-               /* assign the mask for this irq */
-               irq_set_affinity_hint(irq_num, &q_vector->affinity_mask);
+               /* get_cpu_mask returns a static constant mask with
+                * a permanent lifetime so it's ok to use here.
+                */
+               irq_set_affinity_hint(irq_num, get_cpu_mask(q_vector->v_idx));
        }
 
        return 0;
@@ -1456,6 +1458,7 @@ static int i40evf_alloc_q_vectors(struct i40evf_adapter *adapter)
                q_vector->adapter = adapter;
                q_vector->vsi = &adapter->vsi;
                q_vector->v_idx = q_idx;
+               cpumask_copy(&q_vector->affinity_mask, cpu_possible_mask);
                netif_napi_add(adapter->netdev, &q_vector->napi,
                               i40evf_napi_poll, NAPI_POLL_WEIGHT);
        }