Patch "serial: sc16is7xx: setup GPIO controller later in probe" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    serial: sc16is7xx: setup GPIO controller later in probe

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serial-sc16is7xx-setup-gpio-controller-later-in-prob.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 15fa37804c7d5fc31210b2da7c9521506ee9bbc1
Author: Isaac True <isaac.true@xxxxxxxxxxxxx>
Date:   Wed Nov 30 11:55:30 2022 +0100

    serial: sc16is7xx: setup GPIO controller later in probe
    
    [ Upstream commit c8f71b49ee4d28930c4a6798d1969fa91dc4ef3e ]
    
    The GPIO controller component of the sc16is7xx driver is setup too
    early, which can result in a race condition where another device tries
    to utilise the GPIO lines before the sc16is7xx device has finished
    initialising.
    
    This issue manifests itself as an Oops when the GPIO lines are configured:
    
        Unable to handle kernel read from unreadable memory at virtual address
        ...
        pc : sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
        lr : sc16is7xx_gpio_direction_output+0x4c/0x108 [sc16is7xx]
        ...
        Call trace:
        sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
        gpiod_direction_output_raw_commit+0x64/0x318
        gpiod_direction_output+0xb0/0x170
        create_gpio_led+0xec/0x198
        gpio_led_probe+0x16c/0x4f0
        platform_drv_probe+0x5c/0xb0
        really_probe+0xe8/0x448
        driver_probe_device+0xe8/0x138
        __device_attach_driver+0x94/0x118
        bus_for_each_drv+0x8c/0xe0
        __device_attach+0x100/0x1b8
        device_initial_probe+0x28/0x38
        bus_probe_device+0xa4/0xb0
        deferred_probe_work_func+0x90/0xe0
        process_one_work+0x1c4/0x480
        worker_thread+0x54/0x430
        kthread+0x138/0x150
        ret_from_fork+0x10/0x1c
    
    This patch moves the setup of the GPIO controller functions to later in the
    probe function, ensuring the sc16is7xx device has already finished
    initialising by the time other devices try to make use of the GPIO lines.
    The error handling has also been reordered to reflect the new
    initialisation order.
    
    Co-developed-by: Wen-chien Jesse Sung <jesse.sung@xxxxxxxxxxxxx>
    Signed-off-by: Wen-chien Jesse Sung <jesse.sung@xxxxxxxxxxxxx>
    Signed-off-by: Isaac True <isaac.true@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221130105529.698385-1-isaac.true@xxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 524921360ca78..93cf5f7888172 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1426,25 +1426,6 @@ static int sc16is7xx_probe(struct device *dev,
 	}
 	sched_set_fifo(s->kworker_task);
 
-#ifdef CONFIG_GPIOLIB
-	if (devtype->nr_gpio) {
-		/* Setup GPIO cotroller */
-		s->gpio.owner		 = THIS_MODULE;
-		s->gpio.parent		 = dev;
-		s->gpio.label		 = dev_name(dev);
-		s->gpio.direction_input	 = sc16is7xx_gpio_direction_input;
-		s->gpio.get		 = sc16is7xx_gpio_get;
-		s->gpio.direction_output = sc16is7xx_gpio_direction_output;
-		s->gpio.set		 = sc16is7xx_gpio_set;
-		s->gpio.base		 = -1;
-		s->gpio.ngpio		 = devtype->nr_gpio;
-		s->gpio.can_sleep	 = 1;
-		ret = gpiochip_add_data(&s->gpio, s);
-		if (ret)
-			goto out_thread;
-	}
-#endif
-
 	/* reset device, purging any pending irq / data */
 	regmap_write(s->regmap, SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
 			SC16IS7XX_IOCONTROL_SRESET_BIT);
@@ -1521,6 +1502,25 @@ static int sc16is7xx_probe(struct device *dev,
 				s->p[u].irda_mode = true;
 	}
 
+#ifdef CONFIG_GPIOLIB
+	if (devtype->nr_gpio) {
+		/* Setup GPIO cotroller */
+		s->gpio.owner		 = THIS_MODULE;
+		s->gpio.parent		 = dev;
+		s->gpio.label		 = dev_name(dev);
+		s->gpio.direction_input	 = sc16is7xx_gpio_direction_input;
+		s->gpio.get		 = sc16is7xx_gpio_get;
+		s->gpio.direction_output = sc16is7xx_gpio_direction_output;
+		s->gpio.set		 = sc16is7xx_gpio_set;
+		s->gpio.base		 = -1;
+		s->gpio.ngpio		 = devtype->nr_gpio;
+		s->gpio.can_sleep	 = 1;
+		ret = gpiochip_add_data(&s->gpio, s);
+		if (ret)
+			goto out_thread;
+	}
+#endif
+
 	/*
 	 * Setup interrupt. We first try to acquire the IRQ line as level IRQ.
 	 * If that succeeds, we can allow sharing the interrupt as well.
@@ -1540,18 +1540,19 @@ static int sc16is7xx_probe(struct device *dev,
 	if (!ret)
 		return 0;
 
-out_ports:
-	for (i--; i >= 0; i--) {
-		uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
-		clear_bit(s->p[i].port.line, &sc16is7xx_lines);
-	}
-
 #ifdef CONFIG_GPIOLIB
 	if (devtype->nr_gpio)
 		gpiochip_remove(&s->gpio);
 
 out_thread:
 #endif
+
+out_ports:
+	for (i--; i >= 0; i--) {
+		uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
+		clear_bit(s->p[i].port.line, &sc16is7xx_lines);
+	}
+
 	kthread_stop(s->kworker_task);
 
 out_clk:



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