NTB: Disable interrupts and poll under high load

Disable interrupts and poll under high load

Signed-off-by: Jon Mason <jon.mason@intel.com>

3 files changed, 48 insertions, 26 deletions

diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
index 80505aeecf9e..170e8e60cdb7 100644
--- a/drivers/ntb/ntb_hw.c
+++ b/drivers/ntb/ntb_hw.c
@@ -141,6 +141,24 @@ void ntb_unregister_event_callback(struct ntb_device *ndev)
         ndev->event_cb = NULL;
 }
 
+static void ntb_irq_work(unsigned long data)
+{
+        struct ntb_db_cb *db_cb = (struct ntb_db_cb *)data;
+        int rc;
+
+        rc = db_cb->callback(db_cb->data, db_cb->db_num);
+        if (rc)
+                tasklet_schedule(&db_cb->irq_work);
+        else {
+                struct ntb_device *ndev = db_cb->ndev;
+                unsigned long mask;
+
+                mask = readw(ndev->reg_ofs.ldb_mask);
+                clear_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+                writew(mask, ndev->reg_ofs.ldb_mask);
+        }
+}
+
 /**
  * ntb_register_db_callback() - register a callback for doorbell interrupt
  * @ndev: pointer to ntb_device instance
@@ -155,7 +173,7 @@ void ntb_unregister_event_callback(struct ntb_device *ndev)
  * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
  */
 int ntb_register_db_callback(struct ntb_device *ndev, unsigned int idx,
-                             void *data, void (*func)(void *data, int db_num))
+                             void *data, int (*func)(void *data, int db_num))
 {
         unsigned long mask;
 
@@ -166,6 +184,10 @@ int ntb_register_db_callback(struct ntb_device *ndev, unsigned int idx,
 
         ndev->db_cb[idx].callback = func;
         ndev->db_cb[idx].data = data;
+        ndev->db_cb[idx].ndev = ndev;
+
+        tasklet_init(&ndev->db_cb[idx].irq_work, ntb_irq_work,
+                     (unsigned long) &ndev->db_cb[idx]);
 
         /* unmask interrupt */
         mask = readw(ndev->reg_ofs.ldb_mask);
@@ -194,6 +216,8 @@ void ntb_unregister_db_callback(struct ntb_device *ndev, unsigned int idx)
         set_bit(idx * ndev->bits_per_vector, &mask);
         writew(mask, ndev->reg_ofs.ldb_mask);
 
+        tasklet_disable(&ndev->db_cb[idx].irq_work);
+
         ndev->db_cb[idx].callback = NULL;
 }
 
@@ -955,12 +979,16 @@ static irqreturn_t bwd_callback_msix_irq(int irq, void *data)
 {
         struct ntb_db_cb *db_cb = data;
         struct ntb_device *ndev = db_cb->ndev;
+        unsigned long mask;
 
         dev_dbg(&ndev->pdev->dev, "MSI-X irq %d received for DB %d\n", irq,
                 db_cb->db_num);
 
-        if (db_cb->callback)
-                db_cb->callback(db_cb->data, db_cb->db_num);
+        mask = readw(ndev->reg_ofs.ldb_mask);
+        set_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+        writew(mask, ndev->reg_ofs.ldb_mask);
+
+        tasklet_schedule(&db_cb->irq_work);
 
         /* No need to check for the specific HB irq, any interrupt means
          * we're connected.
@@ -976,12 +1004,16 @@ static irqreturn_t xeon_callback_msix_irq(int irq, void *data)
 {
         struct ntb_db_cb *db_cb = data;
         struct ntb_device *ndev = db_cb->ndev;
+        unsigned long mask;
 
         dev_dbg(&ndev->pdev->dev, "MSI-X irq %d received for DB %d\n", irq,
                 db_cb->db_num);
 
-        if (db_cb->callback)
-                db_cb->callback(db_cb->data, db_cb->db_num);
+        mask = readw(ndev->reg_ofs.ldb_mask);
+        set_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+        writew(mask, ndev->reg_ofs.ldb_mask);
+
+        tasklet_schedule(&db_cb->irq_work);
 
         /* On Sandybridge, there are 16 bits in the interrupt register
          * but only 4 vectors.  So, 5 bits are assigned to the first 3
diff --git a/drivers/ntb/ntb_hw.h b/drivers/ntb/ntb_hw.h
index 0a31cedae7d4..bbdb7edca10c 100644
--- a/drivers/ntb/ntb_hw.h
+++ b/drivers/ntb/ntb_hw.h
@@ -106,10 +106,11 @@ struct ntb_mw {
 };
 
 struct ntb_db_cb {
-        void (*callback) (void *data, int db_num);
+        int (*callback)(void *data, int db_num);
         unsigned int db_num;
         void *data;
         struct ntb_device *ndev;
+        struct tasklet_struct irq_work;
 };
 
 struct ntb_device {
@@ -228,8 +229,8 @@ struct ntb_device *ntb_register_transport(struct pci_dev *pdev,
 void ntb_unregister_transport(struct ntb_device *ndev);
 void ntb_set_mw_addr(struct ntb_device *ndev, unsigned int mw, u64 addr);
 int ntb_register_db_callback(struct ntb_device *ndev, unsigned int idx,
-                             void *data, void (*db_cb_func) (void *data,
-                                                             int db_num));
+                             void *data, int (*db_cb_func)(void *data,
+                                                           int db_num));
 void ntb_unregister_db_callback(struct ntb_device *ndev, unsigned int idx);
 int ntb_register_event_callback(struct ntb_device *ndev,
                                 void (*event_cb_func) (void *handle,
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 172501d47600..676937bd679c 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -119,7 +119,6 @@ struct ntb_transport_qp {
 
         void (*rx_handler) (struct ntb_transport_qp *qp, void *qp_data,
                             void *data, int len);
-        struct tasklet_struct rx_work;
         struct list_head rx_pend_q;
         struct list_head rx_free_q;
         spinlock_t ntb_rx_pend_q_lock;
@@ -1188,11 +1187,14 @@ err:
         goto out;
 }
 
-static void ntb_transport_rx(unsigned long data)
+static int ntb_transport_rxc_db(void *data, int db_num)
 {
-        struct ntb_transport_qp *qp = (struct ntb_transport_qp *)data;
+        struct ntb_transport_qp *qp = data;
         int rc, i;
 
+        dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%s: doorbell %d received\n",
+                __func__, db_num);
+
         /* Limit the number of packets processed in a single interrupt to
          * provide fairness to others
          */
@@ -1204,16 +1206,8 @@ static void ntb_transport_rx(unsigned long data)
 
         if (qp->dma_chan)
                 dma_async_issue_pending(qp->dma_chan);
-}
-
-static void ntb_transport_rxc_db(void *data, int db_num)
-{
-        struct ntb_transport_qp *qp = data;
 
-        dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%s: doorbell %d received\n",
-                __func__, db_num);
-
-        tasklet_schedule(&qp->rx_work);
+        return i;
 }
 
 static void ntb_tx_copy_callback(void *data)
@@ -1446,19 +1440,15 @@ ntb_transport_create_queue(void *data, struct pci_dev *pdev,
                              &qp->tx_free_q);
         }
 
-        tasklet_init(&qp->rx_work, ntb_transport_rx, (unsigned long) qp);
-
         rc = ntb_register_db_callback(qp->ndev, free_queue, qp,
                                       ntb_transport_rxc_db);
         if (rc)
-                goto err3;
+                goto err2;
 
         dev_info(&pdev->dev, "NTB Transport QP %d created\n", qp->qp_num);
 
         return qp;
 
-err3:
-        tasklet_disable(&qp->rx_work);
 err2:
         while ((entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q)))
                 kfree(entry);
@@ -1505,7 +1495,6 @@ void ntb_transport_free_queue(struct ntb_transport_qp *qp)
         }
 
         ntb_unregister_db_callback(qp->ndev, qp->qp_num);
-        tasklet_disable(&qp->rx_work);
 
         cancel_delayed_work_sync(&qp->link_work);