On Tue, Dec 4, 2018 at 7:58 AM Enric Balletbo i Serra
<enric.balletbo@xxxxxxxxxxxxx> wrote:
>
> This reverts commit 3aa2177e47878f7e7616da8a2050c44f22301b6e.
>
> That commit triggered a new WARN when unloading the module (see at the
> end of the commit message). When a class_dev is embedded in a structure
> then that class_dev is the thing that controls the lifetime of that
> structure, for that reason device managed allocations can't be used here.
> See Documentation/kobject.txt.
>
> Revert the above patch, so the struct is allocated using kzalloc and we
> have a release function for it that frees the allocated memory, otherwise
> it is broken.
>
> ------------[ cut here ]------------
> Device 'cros_ec' does not have a release() function, it is broken and must be fixed.
> WARNING: CPU: 3 PID: 3675 at drivers/base/core.c:895 device_release+0x80/0x90
> Modules linked in: btusb btrtl btintel btbcm bluetooth ...
> CPU: 3 PID: 3675 Comm: rmmod Not tainted 4.20.0-rc4 #76
> Hardware name: Google Kevin (DT)
> pstate: 40000005 (nZcv daif -PAN -UAO)
> pc : device_release+0x80/0x90
> lr : device_release+0x80/0x90
> sp : ffff00000c47bc70
> x29: ffff00000c47bc70 x28: ffff8000e86b0d40
> x27: 0000000000000000 x26: 0000000000000000
> x25: 0000000056000000 x24: 0000000000000015
> x23: ffff8000f0bbf860 x22: ffff000000d320a0
> x21: ffff8000ee93e100 x20: ffff8000ed931428
> x19: ffff8000ed931418 x18: 0000000000000020
> x17: 0000000000000000 x16: 0000000000000000
> x15: 0000000000000400 x14: 0000000000000143
> x13: 0000000000000000 x12: 0000000000000400
> x11: 0000000000000157 x10: 0000000000000960
> x9 : ffff00000c47b9b0 x8 : ffff8000e86b1700
> x7 : 0000000000000000 x6 : ffff8000f7d520b8
> x5 : ffff8000f7d520b8 x4 : 0000000000000000
> x3 : ffff8000f7d58e68 x2 : ffff8000e86b0d40
> x1 : 37d859939c964800 x0 : 0000000000000000
> Call trace:
> device_release+0x80/0x90
> kobject_put+0x74/0xe8
> device_unregister+0x20/0x30
> ec_device_remove+0x34/0x48 [cros_ec_dev]
> platform_drv_remove+0x28/0x48
> device_release_driver_internal+0x1a8/0x240
> driver_detach+0x40/0x80
> bus_remove_driver+0x54/0xa8
> driver_unregister+0x2c/0x58
> platform_driver_unregister+0x10/0x18
> cros_ec_dev_exit+0x1c/0x2d8 [cros_ec_dev]
> __arm64_sys_delete_module+0x16c/0x1f8
> el0_svc_common+0x84/0xd8
> el0_svc_handler+0x2c/0x80
> el0_svc+0x8/0xc
> ---[ end trace a57c4625f3c60ae8 ]---
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 3aa2177e4787 ("mfd: cros_ec: Use devm_kzalloc for private data")
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
> ---
>
> drivers/mfd/cros_ec_dev.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 8f9d6964173e..b99a194ce5a4 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -263,6 +263,11 @@ static const struct file_operations fops = {
> #endif
> };
>
> +static void cros_ec_class_release(struct device *dev)
> +{
> + kfree(to_cros_ec_dev(dev));
> +}
> +
> static void cros_ec_sensors_register(struct cros_ec_dev *ec)
> {
> /*
> @@ -395,7 +400,7 @@ static int ec_device_probe(struct platform_device *pdev)
> int retval = -ENOMEM;
> struct device *dev = &pdev->dev;
> struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
> - struct cros_ec_dev *ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
> + struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
>
> if (!ec)
> return retval;
> @@ -417,6 +422,7 @@ static int ec_device_probe(struct platform_device *pdev)
> ec->class_dev.devt = MKDEV(ec_major, pdev->id);
> ec->class_dev.class = &cros_class;
> ec->class_dev.parent = dev;
> + ec->class_dev.release = cros_ec_class_release;
>
> retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
> if (retval) {
> --
> 2.19.1
>
