linux-kernel - [PATCH v1 2/2] gpiolib: Check array_info for NULL only once in gpiod_get

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Date:   Tue, 21 Mar 2023 15:54:12 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: [PATCH v1 2/2] gpiolib: Check array_info for NULL only once in gpiod_get_array()

gpiod_get_array() has a long if-else-if branching where each of them
tests for the same variable to be not NULL. Instead, check for NULL
before even going to that flow.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/gpio/gpiolib.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3e94990f1f90..ee24428c5fe3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4294,7 +4294,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 	if (!descs)
 		return ERR_PTR(-ENOMEM);
 
-	for (descs->ndescs = 0; descs->ndescs < count; ) {
+	for (descs->ndescs = 0; descs->ndescs < count; descs->ndescs++) {
 		desc = gpiod_get_index(dev, con_id, descs->ndescs, flags);
 		if (IS_ERR(desc)) {
 			gpiod_put_array(descs);
@@ -4339,8 +4339,13 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 				   count - descs->ndescs);
 			descs->info = array_info;
 		}
+
+		/* If there is no cache for fast bitmap processing path, continue */
+		if (!array_info)
+			continue;
+
 		/* Unmark array members which don't belong to the 'fast' chip */
-		if (array_info && array_info->chip != gc) {
+		if (array_info->chip != gc) {
 			__clear_bit(descs->ndescs, array_info->get_mask);
 			__clear_bit(descs->ndescs, array_info->set_mask);
 		}
@@ -4348,8 +4353,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 		 * Detect array members which belong to the 'fast' chip
 		 * but their pins are not in hardware order.
 		 */
-		else if (array_info &&
-			   gpio_chip_hwgpio(desc) != descs->ndescs) {
+		else if (gpio_chip_hwgpio(desc) != descs->ndescs) {
 			/*
 			 * Don't use fast path if all array members processed so
 			 * far belong to the same chip as this one but its pin
@@ -4363,7 +4367,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 				__clear_bit(descs->ndescs,
 					    array_info->set_mask);
 			}
-		} else if (array_info) {
+		} else {
 			/* Exclude open drain or open source from fast output */
 			if (gpiochip_line_is_open_drain(gc, descs->ndescs) ||
 			    gpiochip_line_is_open_source(gc, descs->ndescs))
@@ -4374,8 +4378,6 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 				__set_bit(descs->ndescs,
 					  array_info->invert_mask);
 		}
-
-		descs->ndescs++;
 	}
 	if (array_info)
 		dev_dbg(dev,
-- 
2.40.0.1.gaa8946217a0b