linux-kernel - [PATCH 17/17] Input: tegra-kbc - use guard notation when acquiring mutex and spinlock

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Message-ID: <20240825051627.2848495-18-dmitry.torokhov@gmail.com>
Date: Sat, 24 Aug 2024 22:16:21 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Laxman Dewangan <ldewangan@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Tony Lindgren <tony@...mide.com>,
	Jeff LaBundy <jeff@...undy.com>,
	linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-tegra@...r.kernel.org
Subject: [PATCH 17/17] Input: tegra-kbc - use guard notation when acquiring mutex and spinlock

This makes the code more compact and error handling more robust
by ensuring that locks are released in all code paths when control
leaves critical section.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/input/keyboard/tegra-kbc.c | 45 +++++++++++++-----------------
 1 file changed, 19 insertions(+), 26 deletions(-)

diff --git a/drivers/input/keyboard/tegra-kbc.c b/drivers/input/keyboard/tegra-kbc.c
index a1765ed8c825..204ba189807e 100644
--- a/drivers/input/keyboard/tegra-kbc.c
+++ b/drivers/input/keyboard/tegra-kbc.c
@@ -241,11 +241,10 @@ static void tegra_kbc_set_fifo_interrupt(struct tegra_kbc *kbc, bool enable)
 static void tegra_kbc_keypress_timer(struct timer_list *t)
 {
 	struct tegra_kbc *kbc = from_timer(kbc, t, timer);
-	unsigned long flags;
 	u32 val;
 	unsigned int i;
 
-	spin_lock_irqsave(&kbc->lock, flags);
+	guard(spinlock_irqsave)(&kbc->lock);
 
 	val = (readl(kbc->mmio + KBC_INT_0) >> 4) & 0xf;
 	if (val) {
@@ -270,17 +269,14 @@ static void tegra_kbc_keypress_timer(struct timer_list *t)
 		/* All keys are released so enable the keypress interrupt */
 		tegra_kbc_set_fifo_interrupt(kbc, true);
 	}
-
-	spin_unlock_irqrestore(&kbc->lock, flags);
 }
 
 static irqreturn_t tegra_kbc_isr(int irq, void *args)
 {
 	struct tegra_kbc *kbc = args;
-	unsigned long flags;
 	u32 val;
 
-	spin_lock_irqsave(&kbc->lock, flags);
+	guard(spinlock_irqsave)(&kbc->lock);
 
 	/*
 	 * Quickly bail out & reenable interrupts if the fifo threshold
@@ -301,8 +297,6 @@ static irqreturn_t tegra_kbc_isr(int irq, void *args)
 		kbc->keypress_caused_wake = true;
 	}
 
-	spin_unlock_irqrestore(&kbc->lock, flags);
-
 	return IRQ_HANDLED;
 }
 
@@ -413,14 +407,13 @@ static int tegra_kbc_start(struct tegra_kbc *kbc)
 
 static void tegra_kbc_stop(struct tegra_kbc *kbc)
 {
-	unsigned long flags;
 	u32 val;
 
-	spin_lock_irqsave(&kbc->lock, flags);
-	val = readl(kbc->mmio + KBC_CONTROL_0);
-	val &= ~1;
-	writel(val, kbc->mmio + KBC_CONTROL_0);
-	spin_unlock_irqrestore(&kbc->lock, flags);
+	scoped_guard(spinlock_irqsave, &kbc->lock) {
+		val = readl(kbc->mmio + KBC_CONTROL_0);
+		val &= ~1;
+		writel(val, kbc->mmio + KBC_CONTROL_0);
+	}
 
 	disable_irq(kbc->irq);
 	del_timer_sync(&kbc->timer);
@@ -724,7 +717,8 @@ static int tegra_kbc_suspend(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct tegra_kbc *kbc = platform_get_drvdata(pdev);
 
-	mutex_lock(&kbc->idev->mutex);
+	guard(mutex)(&kbc->idev->mutex);
+
 	if (device_may_wakeup(&pdev->dev)) {
 		disable_irq(kbc->irq);
 		del_timer_sync(&kbc->timer);
@@ -747,11 +741,9 @@ static int tegra_kbc_suspend(struct device *dev)
 		tegra_kbc_set_keypress_interrupt(kbc, true);
 		enable_irq(kbc->irq);
 		enable_irq_wake(kbc->irq);
-	} else {
-		if (input_device_enabled(kbc->idev))
-			tegra_kbc_stop(kbc);
+	} else if (input_device_enabled(kbc->idev)) {
+		tegra_kbc_stop(kbc);
 	}
-	mutex_unlock(&kbc->idev->mutex);
 
 	return 0;
 }
@@ -760,9 +752,10 @@ static int tegra_kbc_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct tegra_kbc *kbc = platform_get_drvdata(pdev);
-	int err = 0;
+	int err;
+
+	guard(mutex)(&kbc->idev->mutex);
 
-	mutex_lock(&kbc->idev->mutex);
 	if (device_may_wakeup(&pdev->dev)) {
 		disable_irq_wake(kbc->irq);
 		tegra_kbc_setup_wakekeys(kbc, false);
@@ -787,13 +780,13 @@ static int tegra_kbc_resume(struct device *dev)
 			input_report_key(kbc->idev, kbc->wakeup_key, 0);
 			input_sync(kbc->idev);
 		}
-	} else {
-		if (input_device_enabled(kbc->idev))
-			err = tegra_kbc_start(kbc);
+	} else if (input_device_enabled(kbc->idev)) {
+		err = tegra_kbc_start(kbc);
+		if (err)
+			return err;
 	}
-	mutex_unlock(&kbc->idev->mutex);
 
-	return err;
+	return 0;
 }
 
 static DEFINE_SIMPLE_DEV_PM_OPS(tegra_kbc_pm_ops,
-- 
2.46.0.295.g3b9ea8a38a-goog