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();