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>

1 files changed, 35 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/qib/qib_init.c b/drivers/infiniband/hw/qib/qib_init.c
index 76c3e177164d..6d2629990cb3 100644
--- a/drivers/infiniband/hw/qib/qib_init.c
+++ b/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();