[<prev] [next>] [day] [month] [year] [list]
Message-ID: <20251002055727.1488237-1-alex.t.tran@gmail.com>
Date: Wed, 1 Oct 2025 22:57:27 -0700
From: Alex Tran <alex.t.tran@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Bartosz Golaszewski <brgl@...ev.pl>,
linux-gpio@...r.kernel.org,
linux-kernel@...r.kernel.org,
Alex Tran <alex.t.tran@...il.com>,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v2] gpio: 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@...aro.org>
Signed-off-by: Alex Tran <alex.t.tran@...il.com>
---
Changes in v2:
- converted refcnt to type atomic_t
- utilize atomic types API for refcnt
drivers/gpio/gpio-grgpio.c | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index 0c0f97fa14fc..e4fa84e22726 100644
--- 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);
}
}
--
2.51.0
Powered by blists - more mailing lists