IB/qib: Add percpu counter replacing qib_devdata int_counter

This patch replaces the dd->int_counter with a percpu counter.

The maintanance of qib_stats.sps_ints and int_counter are
combined into the new counter.

There are two new functions added to read the counter:
- qib_int_counter (for a particular qib_devdata)
- qib_sps_ints (for all HCAs)

A z_int_counter is added to allow the interrupt detection logic
to determine if interrupts have occured since z_int_counter
was "reset".
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/qib/qib.h

@@ -868,8 +868,10 @@ struct qib_devdata {
 	/* last buffer for user use */
 	u32 lastctxt_piobuf;
 
-	/* saturating counter of (non-port-specific) device interrupts */
-	u32 int_counter;
+	/* reset value */
+	u64 z_int_counter;
+	/* percpu intcounter */
+	u64 __percpu *int_counter;
 
 	/* pio bufs allocated per ctxt */
 	u32 pbufsctxt;
@@ -1449,6 +1451,10 @@ void qib_nomsi(struct qib_devdata *);
 void qib_nomsix(struct qib_devdata *);
 void qib_pcie_getcmd(struct qib_devdata *, u16 *, u8 *, u8 *);
 void qib_pcie_reenable(struct qib_devdata *, u16, u8, u8);
+/* interrupts for device */
+u64 qib_int_counter(struct qib_devdata *);
+/* interrupt for all devices */
+u64 qib_sps_ints(void);
 
 /*
  * dma_addr wrappers - all 0's invalid for hw

drivers/infiniband/hw/qib/qib_fs.c

@@ -105,6 +105,7 @@ static int create_file(const char *name, umode_t mode,
 static ssize_t driver_stats_read(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
 {
+	qib_stats.sps_ints = qib_sps_ints();
 	return simple_read_from_buffer(buf, count, ppos, &qib_stats,
 				       sizeof qib_stats);
 }

drivers/infiniband/hw/qib/qib_iba6120.c

@@ -1634,9 +1634,7 @@ static irqreturn_t qib_6120intr(int irq, void *data)
 		goto bail;
 	}
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	if (unlikely(istat & (~QLOGIC_IB_I_BITSEXTANT |
 			      QLOGIC_IB_I_GPIO | QLOGIC_IB_I_ERROR)))
@@ -1808,7 +1806,8 @@ static int qib_6120_setup_reset(struct qib_devdata *dd)
 	 * isn't set.
 	 */
 	dd->flags &= ~(QIB_INITTED | QIB_PRESENT);
-	dd->int_counter = 0; /* so we check interrupts work again */
+	/* so we check interrupts work again */
+	dd->z_int_counter = qib_int_counter(dd);
 	val = dd->control | QLOGIC_IB_C_RESET;
 	writeq(val, &dd->kregbase[kr_control]);
 	mb(); /* prevent compiler re-ordering around actual reset */

drivers/infiniband/hw/qib/qib_iba7220.c

@@ -1962,10 +1962,7 @@ static irqreturn_t qib_7220intr(int irq, void *data)
 		goto bail;
 	}
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
-
+	this_cpu_inc(*dd->int_counter);
 	if (unlikely(istat & (~QLOGIC_IB_I_BITSEXTANT |
 			      QLOGIC_IB_I_GPIO | QLOGIC_IB_I_ERROR)))
 		unlikely_7220_intr(dd, istat);
@@ -2120,7 +2117,8 @@ static int qib_setup_7220_reset(struct qib_devdata *dd)
 	 * isn't set.
 	 */
 	dd->flags &= ~(QIB_INITTED | QIB_PRESENT);
-	dd->int_counter = 0; /* so we check interrupts work again */
+	/* so we check interrupts work again */
+	dd->z_int_counter = qib_int_counter(dd);
 	val = dd->control | QLOGIC_IB_C_RESET;
 	writeq(val, &dd->kregbase[kr_control]);
 	mb(); /* prevent compiler reordering around actual reset */

drivers/infiniband/hw/qib/qib_iba7322.c

@@ -3115,9 +3115,7 @@ static irqreturn_t qib_7322intr(int irq, void *data)
 		goto bail;
 	}
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* handle "errors" of various kinds first, device ahead of port */
 	if (unlikely(istat & (~QIB_I_BITSEXTANT | QIB_I_GPIO |
@@ -3186,9 +3184,7 @@ static irqreturn_t qib_7322pintr(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, ((1ULL << QIB_I_RCVAVAIL_LSB) |
@@ -3215,9 +3211,7 @@ static irqreturn_t qib_7322bufavail(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, QIB_I_SPIOBUFAVAIL);
@@ -3248,9 +3242,7 @@ static irqreturn_t sdma_intr(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, ppd->hw_pidx ?
@@ -3277,9 +3269,7 @@ static irqreturn_t sdma_idle_intr(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, ppd->hw_pidx ?
@@ -3306,9 +3296,7 @@ static irqreturn_t sdma_progress_intr(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, ppd->hw_pidx ?
@@ -3336,9 +3324,7 @@ static irqreturn_t sdma_cleanup_intr(int irq, void *data)
 		 */
 		return IRQ_HANDLED;
 
-	qib_stats.sps_ints++;
-	if (dd->int_counter != (u32) -1)
-		dd->int_counter++;
+	this_cpu_inc(*dd->int_counter);
 
 	/* Clear the interrupt bit we expect to be set. */
 	qib_write_kreg(dd, kr_intclear, ppd->hw_pidx ?
@@ -3723,7 +3709,8 @@ static int qib_do_7322_reset(struct qib_devdata *dd)
 	dd->pport->cpspec->ibsymdelta = 0;
 	dd->pport->cpspec->iblnkerrdelta = 0;
 	dd->pport->cpspec->ibmalfdelta = 0;
-	dd->int_counter = 0; /* so we check interrupts work again */
+	/* so we check interrupts work again */
+	dd->z_int_counter = qib_int_counter(dd);
 
 	/*
 	 * Keep chip from being accessed until we are ready.  Use

drivers/infiniband/hw/qib/qib_init.c

@@ -525,6 +525,7 @@ static void enable_chip(struct qib_devdata *dd)
 static void verify_interrupt(unsigned long opaque)
 {
 	struct qib_devdata *dd = (struct qib_devdata *) opaque;
+	u64 int_counter;
 
 	if (!dd)
 		return; /* being torn down */
@@ -533,7 +534,8 @@ static void verify_interrupt(unsigned long opaque)
 	 * If we don't have a lid or any interrupts, let the user know and
 	 * don't bother checking again.
 	 */
-	if (dd->int_counter == 0) {
+	int_counter = qib_int_counter(dd) - dd->z_int_counter;
+	if (int_counter == 0) {
 		if (!dd->f_intr_fallback(dd))
 			dev_err(&dd->pcidev->dev,
 				"No interrupts detected, not usable.\n");
@@ -1079,9 +1081,34 @@ void qib_free_devdata(struct qib_devdata *dd)
 #ifdef CONFIG_DEBUG_FS
 	qib_dbg_ibdev_exit(&dd->verbs_dev);
 #endif
+	free_percpu(dd->int_counter);
 	ib_dealloc_device(&dd->verbs_dev.ibdev);
 }
 
+u64 qib_int_counter(struct qib_devdata *dd)
+{
+	int cpu;
+	u64 int_counter = 0;
+
+	for_each_possible_cpu(cpu)
+		int_counter += *per_cpu_ptr(dd->int_counter, cpu);
+	return int_counter;
+}
+
+u64 qib_sps_ints(void)
+{
+	unsigned long flags;
+	struct qib_devdata *dd;
+	u64 sps_ints = 0;
+
+	spin_lock_irqsave(&qib_devs_lock, flags);
+	list_for_each_entry(dd, &qib_dev_list, list) {
+		sps_ints += qib_int_counter(dd);
+	}
+	spin_unlock_irqrestore(&qib_devs_lock, flags);
+	return sps_ints;
+}
+
 /*
  * Allocate our primary per-unit data structure.  Must be done via verbs
  * allocator, because the verbs cleanup process both does cleanup and
@@ -1119,6 +1146,13 @@ struct qib_devdata *qib_alloc_devdata(struct pci_dev *pdev, size_t extra)
 			      "Could not allocate unit ID: error %d\n", -ret);
 		goto bail;
 	}
+	dd->int_counter = alloc_percpu(u64);
+	if (!dd->int_counter) {
+		ret = -ENOMEM;
+		qib_early_err(&pdev->dev,
+			      "Could not allocate per-cpu int_counter\n");
+		goto bail;
+	}
 
 	if (!qib_cpulist_count) {
 		u32 count = num_online_cpus();