qlge: Fix MSI/legacy single interrupt bug.

The chip can issue spurious interrupts for single interrupt
modes. We use disable to clear the condition and allow processing to
continue. Also got rid of legacy specific code since it now needs to
be done on MSI single irq also.

Signed-off-by: Ron Mercer <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/net/qlge/qlge.h

···
 	spinlock_t adapter_lock;
 	spinlock_t hw_lock;
 	spinlock_t stats_lock;
-	spinlock_t legacy_lock;	/* used for maintaining legacy intr sync */
 
 	/* PCI Bus Relative Register Addresses */
 	void __iomem *reg_base;
···
 	u32 intr_count;
 	struct msix_entry *msi_x_entry;
 	struct intr_context intr_context[MAX_RX_RINGS];
-
-	int (*legacy_check) (struct ql_adapter *);
 
 	int tx_ring_count;	/* One per online CPU. */
 	u32 rss_ring_first_cq_id;/* index of first inbound (rss) rx_ring */
···
 void ql_mpi_reset_work(struct work_struct *work);
 int ql_wait_reg_rdy(struct ql_adapter *qdev, u32 reg, u32 bit, u32 ebit);
 void ql_queue_asic_error(struct ql_adapter *qdev);
-void ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr);
+u32 ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr);
 void ql_set_ethtool_ops(struct net_device *ndev);
 int ql_read_xgmac_reg64(struct ql_adapter *qdev, u32 reg, u64 *data);
 

drivers/net/qlge/qlge_main.c

···
  * incremented everytime we queue a worker and decremented everytime
  * a worker finishes.  Once it hits zero we enable the interrupt.
  */
-void ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
+u32 ql_enable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
 {
-	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags)))
+	u32 var = 0;
+	unsigned long hw_flags = 0;
+	struct intr_context *ctx = qdev->intr_context + intr;
+
+	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags) && intr)) {
+		/* Always enable if we're MSIX multi interrupts and
+		 * it's not the default (zeroeth) interrupt.
+		 */
 		ql_write32(qdev, INTR_EN,
-			   qdev->intr_context[intr].intr_en_mask);
-	else {
-		if (qdev->legacy_check)
-			spin_lock(&qdev->legacy_lock);
-		if (atomic_dec_and_test(&qdev->intr_context[intr].irq_cnt)) {
-			QPRINTK(qdev, INTR, ERR, "Enabling interrupt %d.\n",
-				intr);
-			ql_write32(qdev, INTR_EN,
-				   qdev->intr_context[intr].intr_en_mask);
-		} else {
-			QPRINTK(qdev, INTR, ERR,
-				"Skip enable, other queue(s) are active.\n");
-		}
-		if (qdev->legacy_check)
-			spin_unlock(&qdev->legacy_lock);
+			   ctx->intr_en_mask);
+		var = ql_read32(qdev, STS);
+		return var;
 	}
+
+	spin_lock_irqsave(&qdev->hw_lock, hw_flags);
+	if (atomic_dec_and_test(&ctx->irq_cnt)) {
+		ql_write32(qdev, INTR_EN,
+			   ctx->intr_en_mask);
+		var = ql_read32(qdev, STS);
+	}
+	spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);
+	return var;
 }
 
 static u32 ql_disable_completion_interrupt(struct ql_adapter *qdev, u32 intr)
 {
 	u32 var = 0;
+	unsigned long hw_flags;
+	struct intr_context *ctx;
 
-	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags)))
-		goto exit;
-	else if (!atomic_read(&qdev->intr_context[intr].irq_cnt)) {
+	/* HW disables for us if we're MSIX multi interrupts and
+	 * it's not the default (zeroeth) interrupt.
+	 */
+	if (likely(test_bit(QL_MSIX_ENABLED, &qdev->flags) && intr))
+		return 0;
+
+	ctx = qdev->intr_context + intr;
+	spin_lock_irqsave(&qdev->hw_lock, hw_flags);
+	if (!atomic_read(&ctx->irq_cnt)) {
 		ql_write32(qdev, INTR_EN,
-			   qdev->intr_context[intr].intr_dis_mask);
+		ctx->intr_dis_mask);
 		var = ql_read32(qdev, STS);
 	}
-	atomic_inc(&qdev->intr_context[intr].irq_cnt);
-exit:
+	atomic_inc(&ctx->irq_cnt);
+	spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);
 	return var;
 }
 
···
 		 * and enables only if the result is zero.
 		 * So we precharge it here.
 		 */
-		atomic_set(&qdev->intr_context[i].irq_cnt, 1);
+		if (unlikely(!test_bit(QL_MSIX_ENABLED, &qdev->flags) ||
+			i == 0))
+			atomic_set(&qdev->intr_context[i].irq_cnt, 1);
 		ql_enable_completion_interrupt(qdev, i);
 	}
 
···
 	return IRQ_HANDLED;
 }
 
-/* We check here to see if we're already handling a legacy
- * interrupt.  If we are, then it must belong to another
- * chip with which we're sharing the interrupt line.
- */
-int ql_legacy_check(struct ql_adapter *qdev)
-{
-	int err;
-	spin_lock(&qdev->legacy_lock);
-	err = atomic_read(&qdev->intr_context[0].irq_cnt);
-	spin_unlock(&qdev->legacy_lock);
-	return err;
-}
-
 /* This handles a fatal error, MPI activity, and the default
  * rx_ring in an MSI-X multiple vector environment.
  * In MSI/Legacy environment it also process the rest of
···
 	int i;
 	int work_done = 0;
 
-	if (qdev->legacy_check && qdev->legacy_check(qdev)) {
-		QPRINTK(qdev, INTR, INFO, "Already busy, not our interrupt.\n");
-		return IRQ_NONE;	/* Not our interrupt */
+	spin_lock(&qdev->hw_lock);
+	if (atomic_read(&qdev->intr_context[0].irq_cnt)) {
+		QPRINTK(qdev, INTR, DEBUG, "Shared Interrupt, Not ours!\n");
+		spin_unlock(&qdev->hw_lock);
+		return IRQ_NONE;
 	}
+	spin_unlock(&qdev->hw_lock);
 
-	var = ql_read32(qdev, STS);
+	var = ql_disable_completion_interrupt(qdev, intr_context->intr);
 
 	/*
 	 * Check for fatal error.
···
 			}
 		}
 	}
+	ql_enable_completion_interrupt(qdev, intr_context->intr);
 	return work_done ? IRQ_HANDLED : IRQ_NONE;
 }
 
···
 		}
 	}
 	irq_type = LEG_IRQ;
-	spin_lock_init(&qdev->legacy_lock);
-	qdev->legacy_check = ql_legacy_check;
 	QPRINTK(qdev, IFUP, DEBUG, "Running with legacy interrupts.\n");
 }