Hi
2017-03-03 16:09 GMT+01:00 Alexandre Belloni <
alexandre.bell...@free-electrons.com>:
> On 03/03/2017 at 15:46:36 +0100, Michal Simek wrote:
> > This is the function which is making the difference.
> >
> > It was added by John Stultz:
> > "timers: Introduce in-kernel alarm-timer interface"
> > (sha1: ff3ead96d17f47ee70c294a5cc2cce9b61e82f0f)
> >
> > Probe function has device_init_wakeup(&pdev->dev, 1);
> > That's why reference is taken (get_device() below)
> >
> > static int alarmtimer_rtc_add_device(struct device *dev,
> > struct class_interface *class_intf)
> > {
> > unsigned long flags;
> > struct rtc_device *rtc = to_rtc_device(dev);
> >
> > if (rtcdev)
> > return -EBUSY;
> >
> > pr_info("%s\n", __func__);
> >
> > if (!rtc->ops->set_alarm)
> > return -1;
> >
> > pr_info("%s\n", __func__);
> >
> > if (!device_may_wakeup(rtc->dev.parent))
> > return -1;
> >
> > spin_lock_irqsave(&rtcdev_lock, flags);
> > if (!rtcdev) {
> > rtcdev = rtc;
> > /* hold a reference so it doesn't go away */
> > get_device(dev);
> > }
> > spin_unlock_irqrestore(&rtcdev_lock, flags);
> > return 0;
> > }
> >
> > And in remove function device_init_wakeup(&pdev->dev, 0);
> > But because there is still a reference rtc_device_release() is not
> > called and ida is not freed.
> >
> > Generic question which I think should be asked if in this situation
> > driver should be modular or not.
> > If driver can be modular then somewhere should be put_device().
> >
>
> From a quick look, I'd say the issue is coming from
> 8bc0dafb5cf38a19484dfb16e2c6d29e85820046 which removed the call to
> rtc_class_open so you can actually unload the module.
>
>
This is from 2011 which is kind of surprising.
M
--
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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