From: Isaac True isaac.true@canonical.com
[ 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@canonical.com Signed-off-by: Wen-chien Jesse Sung jesse.sung@canonical.com Signed-off-by: Isaac True isaac.true@canonical.com Link: https://lore.kernel.org/r/20221130105529.698385-1-isaac.true@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/sc16is7xx.c | 51 +++++++++++++++++----------------- 1 file changed, 26 insertions(+), 25 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 39f92eb1e6989..29c94be091596 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1423,25 +1423,6 @@ 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); @@ -1518,6 +1499,25 @@ 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. @@ -1537,18 +1537,19 @@ 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: