gpio: grgpio: call request_irq after incrementing the reference count

Remove extraneous dropping of the lock just to call 'request_irq'
and locking again afterwards. Increment reference count
before calling 'request_irq'. Rollback reference count if
'request_irq' fails.

Suggested-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Alex Tran <alex.t.tran@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index 0c0f97fa14fc9df05274deeda8f8e17fa68fa9dd..e4fa84e227262b76cf1fc0d5974415a7ad2654ea 100644 (file)
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -46,7 +46,7 @@
 
 /* Structure for an irq of the core - called an underlying irq */
 struct grgpio_uirq {
-       u8 refcnt; /* Reference counter to manage requesting/freeing of uirq */
+       atomic_t refcnt; /* Reference counter to manage requesting/freeing of uirq */
        u8 uirq; /* Underlying irq of the gpio driver */
 };
 
@@ -242,30 +242,22 @@ static int grgpio_irq_map(struct irq_domain *d, unsigned int irq,
                irq, offset);
 
        gpio_generic_chip_lock_irqsave(&priv->chip, flags);
-
-       /* Request underlying irq if not already requested */
        lirq->irq = irq;
        uirq = &priv->uirqs[lirq->index];
-       if (uirq->refcnt == 0) {
-               /*
-                * FIXME: This is not how locking works at all, you can't just
-                * release the lock for a moment to do something that can't
-                * sleep...
-                */
-               gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
+       gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
+
+       /* Request underlying irq if not already requested */
+       if (atomic_fetch_add(1, &uirq->refcnt) == 0) {
                ret = request_irq(uirq->uirq, grgpio_irq_handler, 0,
                                  dev_name(priv->dev), priv);
                if (ret) {
                        dev_err(priv->dev,
                                "Could not request underlying irq %d\n",
                                uirq->uirq);
+                       atomic_dec(&uirq->refcnt); /* rollback */
                        return ret;
                }
-               gpio_generic_chip_lock_irqsave(&priv->chip, flags);
        }
-       uirq->refcnt++;
-
-       gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
 
        /* Setup irq  */
        irq_set_chip_data(irq, priv);
@@ -306,8 +298,7 @@ static void grgpio_irq_unmap(struct irq_domain *d, unsigned int irq)
 
        if (index >= 0) {
                uirq = &priv->uirqs[lirq->index];
-               uirq->refcnt--;
-               if (uirq->refcnt == 0) {
+               if (atomic_dec_and_test(&uirq->refcnt)) {
                        gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
                        free_irq(uirq->uirq, priv);
                        return;
@@ -434,6 +425,7 @@ static int grgpio_probe(struct platform_device *ofdev)
                                continue;
                        }
                        priv->uirqs[lirq->index].uirq = ret;
+                       atomic_set(&priv->uirqs[lirq->index].refcnt, 0);
                }
        }