[04/22] gpio: provide and use gpiod_get_label()

Message ID	20240130124828.14678-5-brgl@bgdev.pl
State	Superseded
Headers	show Received: from mail-wr1-f41.google.com (mail-wr1-f41.google.com [209.85.221.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E8586BB2B for <linux-gpio@vger.kernel.org>; Tue, 30 Jan 2024 12:48:45 +0000 (UTC) From: Bartosz Golaszewski <brgl@bgdev.pl> To: Linus Walleij <linus.walleij@linaro.org>, Kent Gibson <warthog618@gmail.com>, Alex Elder <elder@linaro.org>, Geert Uytterhoeven <geert+renesas@glider.be>, "Paul E . McKenney" <paulmck@kernel.org>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Wolfram Sang <wsa@the-dreams.de> Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Subject: [PATCH 04/22] gpio: provide and use gpiod_get_label() Date: Tue, 30 Jan 2024 13:48:10 +0100 Message-Id: <20240130124828.14678-5-brgl@bgdev.pl> In-Reply-To: <20240130124828.14678-1-brgl@bgdev.pl> References: <20240130124828.14678-1-brgl@bgdev.pl> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	gpio: rework locking and object life-time control \| expand [00/22] gpio: rework locking and object life-time control [01/22] gpio: protect the list of GPIO devices with SRCU [02/22] gpio: of: assign and read the hog pointer atomically [03/22] gpio: remove unused logging helpers [04/22] gpio: provide and use gpiod_get_label() [05/22] gpio: don't set label from irq helpers [06/22] gpio: add SRCU infrastructure to struct gpio_desc [07/22] gpio: protect the descriptor label with SRCU [08/22] gpio: sysfs: use gpio_device_find() to iterate over existing devices [09/22] gpio: remove gpio_lock [10/22] gpio: reinforce desc->flags handling [11/22] gpio: remove unneeded code from gpio_device_get_desc() [12/22] gpio: sysfs: extend the critical section for unregistering sysfs devices [13/22] gpio: sysfs: pass the GPIO device - not chip - to sysfs callbacks [14/22] gpio: cdev: replace gpiochip_get_desc() with gpio_device_get_desc() [15/22] gpio: cdev: don't access gdev->chip if it's not needed [16/22] gpio: reduce the functionality of validate_desc() [17/22] gpio: remove unnecessary checks from gpiod_to_chip() [18/22] gpio: add the can_sleep flag to struct gpio_device [19/22] gpio: add SRCU infrastructure to struct gpio_device [20/22] gpio: protect the pointer to gpio_chip in gpio_device with SRCU [21/22] gpio: remove the RW semaphore from the GPIO device [22/22] gpio: mark unsafe gpio_chip manipulators as deprecated

Message ID

20240130124828.14678-5-brgl@bgdev.pl

State

Superseded

Headers

From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Linus Walleij <linus.walleij@linaro.org>,
	Kent Gibson <warthog618@gmail.com>,
	Alex Elder <elder@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Wolfram Sang <wsa@the-dreams.de>
Cc: linux-gpio@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Subject: [PATCH 04/22] gpio: provide and use gpiod_get_label()
Date: Tue, 30 Jan 2024 13:48:10 +0100
Message-Id: <20240130124828.14678-5-brgl@bgdev.pl>
In-Reply-To: <20240130124828.14678-1-brgl@bgdev.pl>
References: <20240130124828.14678-1-brgl@bgdev.pl>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Series

gpio: rework locking and object life-time control | expand

Commit Message

Bartosz Golaszewski Jan. 30, 2024, 12:48 p.m. UTC

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

First: let's implement and use the getter where it's applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-cdev.c | 4 ++--
 drivers/gpio/gpiolib.c      | 9 +++++++--
 drivers/gpio/gpiolib.h      | 1 +
 3 files changed, 10 insertions(+), 4 deletions(-)

Comments

Linus Walleij Jan. 31, 2024, 7:36 p.m. UTC | #1

On Tue, Jan 30, 2024 at 1:48 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> We will soon serialize access to the descriptor label using SRCU. The
> write-side of the protection will require calling synchronize_srcu()
> which must not be called from atomic context. We have two irq helpers:
> gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
> if the GPIO is not requested but is being used as interrupt. They are
> called with a spinlock held from the interrupt subsystem.
>
> They must not do it if we are to use SRCU so instead let's move the
> special corner case to a dedicated getter.
>
> First: let's implement and use the getter where it's applicable.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

After seeing the clever trick in the next patch I realized why
you do this.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 34d6712fa07c..2c0a0700762d 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -2305,8 +2305,8 @@  static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 		if (desc->name)
 			strscpy(info->name, desc->name, sizeof(info->name));
 
-		if (desc->label)
-			strscpy(info->consumer, desc->label,
+		if (gpiod_get_label(desc))
+			strscpy(info->consumer, gpiod_get_label(desc),
 				sizeof(info->consumer));
 
 		dflags = READ_ONCE(desc->flags);
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 543d80457647..d0a2f014dacd 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -105,6 +105,11 @@  static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gc);
 
 static bool gpiolib_initialized;
 
+const char *gpiod_get_label(struct gpio_desc *desc)
+{
+	return desc->label;
+}
+
 static inline void desc_set_label(struct gpio_desc *d, const char *label)
 {
 	d->label = label;
@@ -2382,7 +2387,7 @@  char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
 	 *
 	 * Until this happens, this allocation needs to be atomic.
 	 */
-	label = kstrdup(desc->label, GFP_ATOMIC);
+	label = kstrdup(gpiod_get_label(desc), GFP_ATOMIC);
 	if (!label)
 		return ERR_PTR(-ENOMEM);
 
@@ -4719,7 +4724,7 @@  static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
 			is_irq = test_bit(FLAG_USED_AS_IRQ, &desc->flags);
 			active_low = test_bit(FLAG_ACTIVE_LOW, &desc->flags);
 			seq_printf(s, " gpio-%-3d (%-20.20s|%-20.20s) %s %s %s%s\n",
-				   gpio, desc->name ?: "", desc->label,
+				   gpio, desc->name ?: "", gpiod_get_label(desc),
 				   is_out ? "out" : "in ",
 				   value >= 0 ? (value ? "hi" : "lo") : "?  ",
 				   is_irq ? "IRQ " : "",
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index c3ae5bfa3f2e..1058f326fe2b 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -208,6 +208,7 @@  int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce);
 int gpiod_hog(struct gpio_desc *desc, const char *name,
 		unsigned long lflags, enum gpiod_flags dflags);
 int gpiochip_get_ngpios(struct gpio_chip *gc, struct device *dev);
+const char *gpiod_get_label(struct gpio_desc *desc);
 
 /*
  * Return the GPIO number of the passed descriptor relative to its chip

[04/22] gpio: provide and use gpiod_get_label()

Commit Message

Comments

Patch