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>

6 files changed, 59 insertions, 34 deletions

diff --git a/drivers/infiniband/hw/qib/qib.h b/drivers/infiniband/hw/qib/qib.h
index 1946101419a3..f044430ed98e 100644
--- a/drivers/infiniband/hw/qib/qib.h
+++ b/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
diff --git a/drivers/infiniband/hw/qib/qib_fs.c b/drivers/infiniband/hw/qib/qib_fs.c
index c61e2a92b3c1..cab610ccd50e 100644
--- a/drivers/infiniband/hw/qib/qib_fs.c
+++ b/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);
 }
diff --git a/drivers/infiniband/hw/qib/qib_iba6120.c b/drivers/infiniband/hw/qib/qib_iba6120.c
index 84e593d6007b..b9bea2ebfd4a 100644
--- a/drivers/infiniband/hw/qib/qib_iba6120.c
+++ b/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 */
diff --git a/drivers/infiniband/hw/qib/qib_iba7220.c b/drivers/infiniband/hw/qib/qib_iba7220.c
index 454c2e7668fe..28063d4c225b 100644
--- a/drivers/infiniband/hw/qib/qib_iba7220.c
+++ b/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 */
diff --git a/drivers/infiniband/hw/qib/qib_iba7322.c b/drivers/infiniband/hw/qib/qib_iba7322.c
index d1bd21319d7d..8441579decd9 100644
--- a/drivers/infiniband/hw/qib/qib_iba7322.c
+++ b/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
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();