Messages in this thread | | | Date | Wed, 19 Dec 2012 08:55:57 +0100 | From | Alexander Holler <> | Subject | Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver |
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Am 19.12.2012 08:45, schrieb Andrew Morton: > On Wed, 19 Dec 2012 08:37:07 +0100 Alexander Holler <holler@ahsoftware.de> wrote: > >> Am 19.12.2012 01:46, schrieb Andrew Morton: >>> On Thu, 2 Aug 2012 16:53:25 -0700 >>> Vincent Palatin <vpalatin@chromium.org> wrote: >>> >>>> When calling rtc_device_unregister, we are not freeing the id used by the >>>> driver. >>>> So when doing a unload/load cycle for a RTC driver (e.g. rmmod rtc_cmos >>>> && modprobe rtc_cmos), its id is incremented by one. As a consequence, >>>> we no longer have neither an rtc0 driver nor a /proc/driver/rtc (as it >>>> only exists for the first driver). >>>> >>>> Signed-off-by: Vincent Palatin <vpalatin@chromium.org> >>>> --- >>>> drivers/rtc/class.c | 1 + >>>> 1 files changed, 1 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c >>>> index dc4c274..37b1d82 100644 >>>> --- a/drivers/rtc/class.c >>>> +++ b/drivers/rtc/class.c >>>> @@ -238,6 +238,7 @@ void rtc_device_unregister(struct rtc_device *rtc) >>>> rtc_proc_del_device(rtc); >>>> device_unregister(&rtc->dev); >>>> rtc->ops = NULL; >>>> + ida_simple_remove(&rtc_ida, rtc->id); >>>> mutex_unlock(&rtc->ops_lock); >>>> put_device(&rtc->dev); >>>> } >>> >>> Now I think about it, this shouldn't have been needed? >>> >>> That put_device() should call rtc_device_release(), which does the >>> ida_simple_remove(). Isn't that working? >> >> It is, see the mini-thread, patch and my comment here: >> >> https://lkml.org/lkml/2012/12/6/152 >> >> Maybe it would be better to move the ida_simple_remove from the >> rtc_device_release to rt_device_unregister as I've hinted in the above >> comment. That would make it easier to spot the ida_simple_remove(). > > I'm all confused. > > Lothar's patch simply reverts Vincent's patch. And that appears to be > the correct thing to so, as the ida_simple_remove() in > rtc_device_release() should be sufficient. > > But apparently that doesn't work, because Vincent was seeing the RTC > ID's increment rather than getting reused. > > Is it the case that rtc_device_release() is not being called sometimes? > If so, under what circumstances?
Maybe something (sysfs or whatever) still has a reference to it. Vincent should check that.
But I'm sure the ID will be recycled with that put_device() in unregister because I've got the same warning as Lothar did when (porperly) removing an RTC (with kernel 3.7).
Regards,
Alexander
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