Re: [PATCH 2/2] gpiolib: Defer gpio device setup until after gpiolib initialization

Guenter Roeck
2016-04-01T00:53:05Z

On Fri, Apr 01, 2016 at 10:29:11AM +1000, Greg Ungerer wrote:
> Hi Guenter,
>
> On 01/04/16 01:11, Guenter Roeck wrote:
> > Since commit ff2b13592299 ("gpio: make the gpiochip a real device"),
> > attempts to add a gpio chip prior to gpiolib initialization cause
> > the system to crash. This happens because gpio_bus_type has not been
> > registered yet. Defer creating gpio devices until after gpiolib has
> > been initialized to fix the problem.
> >
> > Cc: Greg Ungerer <gerg@uclinux.org>
> > Cc: Alexandre Courbot <gnurou@gmail.com>
> > Fixes: ff2b13592299 ("gpio: make the gpiochip a real device")
> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>
> Thanks for putting these patches together.
> I can now boot all my boards again with them applied :-)
>
> But, I am seeing an issue on one of my targets during boot:
>
> ...
> Mount-cache hash table entries: 2048 (order: 0, 8192 bytes)
> Mountpoint-cache hash table entries: 2048 (order: 0, 8192 bytes)
> clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 0x000da0e6
> sysfs: cannot create duplicate filename '/bus/gpio'
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.6.0-rc1-dirty #1
> Stack from 0383de38:
> 0383de38 0021f692 00027eb0 03841000 002134f2 038261b0 0382f688 00111c1e
> 00027efe 0021ccc4 0000001f 000da0e6 00000009 00000000 0383de74 0021cc91
> 0383de90 0383df8c 000da0e6 0021ccc4 0000001f 0021cc91 03841000 002134f2
> 038261b0 0382f688 00000000 000da1f0 038261b0 002134f2 0382f688 0382f688
> 00111d86 0382f688 00000000 0382f688 0382f688 0382f680 0024fe84 0002118e
> 0383df8c 0382f688 00112094 0382f688 00000000 0013f5dc 0382f680 00000001
> Call Trace:
> ...
> ---[ end trace 013025e2024d8831 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at lib/kobject.c:240 0x00111fc0
> kobject_add_internal failed for gpio with -EEXIST, don't try to register things with the same name in the same directory.
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Tainted: G W 4.6.0-rc1-dirty #1
> Stack from 0383de68:
> 0383de68 0021f692 00027eb0 ffffffef 0382f688 00000000 0382f688 00111a26
> 00027efe 0021f817 000000f0 00111fc0 00000009 00000000 0383dea4 0021f8cd
> 0383dec0 0383df8c 00111fc0 0021f817 000000f0 0021f8cd 002069e9 002134f2
> 0382f688 0382f680 0024fe84 0002118e 0383df8c 0382f688 00112094 0382f688
> 00000000 0013f5dc 0382f680 00000001 0000001f 002600de 00265950 0002118e
> 0383df8c 002600f2 0024fe84 00000001 002600de 00265950 0002118e 00021274
> Call Trace:
> ...
> ---[ end trace 013025e2024d8832 ]---
> gpiolib: could not register GPIO bus type
> NET: Registered protocol family 16

Probably coldfire ?

arch/m68k/coldfire/gpio.c:

static struct bus_type mcfgpio_subsys = {
.name = "gpio",
.dev_name = "gpio",
};

No idea what to do about that. Can that bus be renamed ?

>
> The boot otherwise continues and is successful.
>
Thanks for testing!

Guenter

> Regards
> Greg
>
>
> > ---
> > drivers/gpio/gpiolib.c | 98 ++++++++++++++++++++++++++++++++++----------------
> > 1 file changed, 67 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index f1531070814d..8bb24dc8dc3d 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -68,6 +68,7 @@ LIST_HEAD(gpio_devices);
> > static void gpiochip_free_hogs(struct gpio_chip *chip);
> > static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
> >
> > +static bool gpiolib_initialized;
> >
> > static inline void desc_set_label(struct gpio_desc *d, const char *label)
> > {
> > @@ -445,6 +446,58 @@ static void gpiodevice_release(struct device *dev)
> > kfree(gdev);
> > }
> >
> > +static int gpiochip_setup_dev(struct gpio_device *gdev)
> > +{
> > + int status;
> > +
> > + cdev_init(&gdev->chrdev, &gpio_fileops);
> > + gdev->chrdev.owner = THIS_MODULE;
> > + gdev->chrdev.kobj.parent = &gdev->dev.kobj;
> > + gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);
> > + status = cdev_add(&gdev->chrdev, gdev->dev.devt, 1);
> > + if (status < 0)
> > + chip_warn(gdev->chip, "failed to add char device %d:%d\n",
> > + MAJOR(gpio_devt), gdev->id);
> > + else
> > + chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",
> > + MAJOR(gpio_devt), gdev->id);
> > + status = device_add(&gdev->dev);
> > + if (status)
> > + goto err_remove_chardev;
> > +
> > + status = gpiochip_sysfs_register(gdev);
> > + if (status)
> > + goto err_remove_device;
> > +
> > + /* From this point, the .release() function cleans up gpio_device */
> > + gdev->dev.release = gpiodevice_release;
> > + get_device(&gdev->dev);
> > + pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",
> > + __func__, gdev->base, gdev->base + gdev->ngpio - 1,
> > + dev_name(&gdev->dev), gdev->chip->label ? : "generic");
> > +
> > + return 0;
> > +
> > +err_remove_device:
> > + device_del(&gdev->dev);
> > +err_remove_chardev:
> > + cdev_del(&gdev->chrdev);
> > + return status;
> > +}
> > +
> > +static void gpiochip_setup_devs(void)
> > +{
> > + struct gpio_device *gdev;
> > + int err;
> > +
> > + list_for_each_entry(gdev, &gpio_devices, list) {
> > + err = gpiochip_setup_dev(gdev);
> > + if (err)
> > + pr_err("%s: Failed to initialize gpio device (%d)\n",
> > + dev_name(&gdev->dev), err);
> > + }
> > +}
> > +
> > /**
> > * gpiochip_add_data() - register a gpio_chip
> > * @chip: the chip to register, with chip->base initialized
> > @@ -459,6 +512,9 @@ static void gpiodevice_release(struct device *dev)
> > * the gpio framework's arch_initcall(). Otherwise sysfs initialization
> > * for GPIOs will fail rudely.
> > *
> > + * gpiochip_add_data() must only be called after gpiolib initialization,
> > + * ie after core_initcall().
> > + *
> > * If chip->base is negative, this requests dynamic assignment of
> > * a range of valid GPIOs.
> > */
> > @@ -515,7 +571,7 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
> > if (chip->ngpio == 0) {
> > chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
> > status = -EINVAL;
> > - goto err_free_gdev;
> > + goto err_free_descs;
> > }
> >
> > if (chip->label)
> > @@ -597,39 +653,16 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
> > * we get a device node entry in sysfs under
> > * /sys/bus/gpio/devices/gpiochipN/dev that can be used for
> > * coldplug of device nodes and other udev business.
> > + * We can do this only if gpiolib has been initialized.
> > + * Otherwise, defer until later.
> > */
> > - cdev_init(&gdev->chrdev, &gpio_fileops);
> > - gdev->chrdev.owner = THIS_MODULE;
> > - gdev->chrdev.kobj.parent = &gdev->dev.kobj;
> > - gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);
> > - status = cdev_add(&gdev->chrdev, gdev->dev.devt, 1);
> > - if (status < 0)
> > - chip_warn(chip, "failed to add char device %d:%d\n",
> > - MAJOR(gpio_devt), gdev->id);
> > - else
> > - chip_dbg(chip, "added GPIO chardev (%d:%d)\n",
> > - MAJOR(gpio_devt), gdev->id);
> > - status = device_add(&gdev->dev);
> > - if (status)
> > - goto err_remove_chardev;
> > -
> > - status = gpiochip_sysfs_register(gdev);
> > - if (status)
> > - goto err_remove_device;
> > -
> > - /* From this point, the .release() function cleans up gpio_device */
> > - gdev->dev.release = gpiodevice_release;
> > - get_device(&gdev->dev);
> > - pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",
> > - __func__, gdev->base, gdev->base + gdev->ngpio - 1,
> > - dev_name(&gdev->dev), chip->label ? : "generic");
> > -
> > + if (gpiolib_initialized) {
> > + status = gpiochip_setup_dev(gdev);
> > + if (status)
> > + goto err_remove_chip;
> > + }
> > return 0;
> >
> > -err_remove_device:
> > - device_del(&gdev->dev);
> > -err_remove_chardev:
> > - cdev_del(&gdev->chrdev);
> > err_remove_chip:
> > acpi_gpiochip_remove(chip);
> > gpiochip_free_hogs(chip);
> > @@ -2834,6 +2867,9 @@ static int __init gpiolib_dev_init(void)
> > if (ret < 0) {
> > pr_err("gpiolib: failed to allocate char dev region\n");
> > bus_unregister(&gpio_bus_type);
> > + } else {
> > + gpiolib_initialized = true;
> > + gpiochip_setup_devs();
> > }
> > return ret;
> > }
> >
>