2016-04-18 15:15 GMT+09:00 Qianyu Gong <[email protected]>:
> Hi Akinobu,
>
>
>
> I got an rtc call trace when booting 4.6 kernel on our board and I found it
>
> was caused by this patch:
>
>
>
> commit fc1dcb0b39dbb10d3290f2fcd6e154670f699166
>
> Author: Akinobu Mita <[email protected]>
>
> Date: Mon Mar 7 00:27:53 2016 +0900
>
>
>
> rtc: ds3232: use rtc->ops_lock to protect alarm operations
>
>
>
> ds3232->mutex is used to protect for alarm operations which
>
> need to access status and control registers.
>
>
>
> But we can use rtc->ops_lock instead. rtc->ops_lock is held when most
>
> of rtc_class_ops methods are called, so we only need to explicitly
>
> acquire it from irq handler in order to protect form concurrent
>
> accesses.
>
>
>
> Signed-off-by: Akinobu Mita <[email protected]>
>
> Signed-off-by: Alexandre Belloni <[email protected]
>
>
>
> The problem is that rtc->ops_lock would be accessed in ds3232_irq()
>
> without being initialized as rtc_device_register() is called too late.
You have already identified the root cause of this issue.
> As I’m not familiar with rtc things, could I just revert the patch or you
> already
>
> have a solution to this problem? Thanks in advance.
Could you check if the problem is resolved by moving the call of
devm_rtc_device_register() from the end of ds3232_probe() to just
before registering irq handler?
> -----Original Message-----
> From: Akinobu Mita [mailto:[email protected]]
> Sent: Monday, April 18, 2016 9:02 PM
> To: Qianyu Gong <[email protected]>
> Cc: [email protected]; Mingkai Hu <[email protected]>;
> [email protected]; [email protected]
> Subject: Re: rtc ds3232 call trace in kernel
>
> 2016-04-18 15:15 GMT+09:00 Qianyu Gong <[email protected]>:
> > Hi Akinobu,
> >
> >
> >
> > I got an rtc call trace when booting 4.6 kernel on our board and I
> > found it
> >
> > was caused by this patch:
> >
> >
> >
> > commit fc1dcb0b39dbb10d3290f2fcd6e154670f699166
> >
> > Author: Akinobu Mita <[email protected]>
> >
> > Date: Mon Mar 7 00:27:53 2016 +0900
> >
> >
> >
> > rtc: ds3232: use rtc->ops_lock to protect alarm operations
> >
> >
> >
> > ds3232->mutex is used to protect for alarm operations which
> >
> > need to access status and control registers.
> >
> >
> >
> > But we can use rtc->ops_lock instead. rtc->ops_lock is held when
> > most
> >
> > of rtc_class_ops methods are called, so we only need to explicitly
> >
> > acquire it from irq handler in order to protect form concurrent
> >
> > accesses.
> >
> >
> >
> > Signed-off-by: Akinobu Mita <[email protected]>
> >
> > Signed-off-by: Alexandre Belloni <[email protected]
> >
> >
> >
> > The problem is that rtc->ops_lock would be accessed in ds3232_irq()
> >
> > without being initialized as rtc_device_register() is called too late.
>
> You have already identified the root cause of this issue.
>
> > As I’m not familiar with rtc things, could I just revert the patch or
> > you already
> >
> > have a solution to this problem? Thanks in advance.
>
> Could you check if the problem is resolved by moving the call of
> devm_rtc_device_register() from the end of ds3232_probe() to just before
> registering irq handler?
Yes. It works(no call trace now).
Regards,
Qianyu
2016-04-19 11:36 GMT+09:00 Qianyu Gong <[email protected]>:
>
>> -----Original Message-----
>> From: Akinobu Mita [mailto:[email protected]]
>> Sent: Monday, April 18, 2016 9:02 PM
>> To: Qianyu Gong <[email protected]>
>> Cc: [email protected]; Mingkai Hu <[email protected]>;
>> [email protected]; [email protected]
>> Subject: Re: rtc ds3232 call trace in kernel
>>
>> 2016-04-18 15:15 GMT+09:00 Qianyu Gong <[email protected]>:
>> > Hi Akinobu,
>> >
>> >
>> >
>> > I got an rtc call trace when booting 4.6 kernel on our board and I
>> > found it
>> >
>> > was caused by this patch:
>> >
>> >
>> >
>> > commit fc1dcb0b39dbb10d3290f2fcd6e154670f699166
>> >
>> > Author: Akinobu Mita <[email protected]>
>> >
>> > Date: Mon Mar 7 00:27:53 2016 +0900
>> >
>> >
>> >
>> > rtc: ds3232: use rtc->ops_lock to protect alarm operations
>> >
>> >
>> >
>> > ds3232->mutex is used to protect for alarm operations which
>> >
>> > need to access status and control registers.
>> >
>> >
>> >
>> > But we can use rtc->ops_lock instead. rtc->ops_lock is held when
>> > most
>> >
>> > of rtc_class_ops methods are called, so we only need to explicitly
>> >
>> > acquire it from irq handler in order to protect form concurrent
>> >
>> > accesses.
>> >
>> >
>> >
>> > Signed-off-by: Akinobu Mita <[email protected]>
>> >
>> > Signed-off-by: Alexandre Belloni <[email protected]
>> >
>> >
>> >
>> > The problem is that rtc->ops_lock would be accessed in ds3232_irq()
>> >
>> > without being initialized as rtc_device_register() is called too late.
>>
>> You have already identified the root cause of this issue.
>>
>> > As I’m not familiar with rtc things, could I just revert the patch or
>> > you already
>> >
>> > have a solution to this problem? Thanks in advance.
>>
>> Could you check if the problem is resolved by moving the call of
>> devm_rtc_device_register() from the end of ds3232_probe() to just before
>> registering irq handler?
>
> Yes. It works(no call trace now).
Thanks for testing. Do you mind submitting your patch to
[email protected] ?
> -----Original Message-----
> From: Akinobu Mita [mailto:[email protected]]
> Sent: Tuesday, April 19, 2016 11:58 AM
> To: Qianyu Gong <[email protected]>
> Cc: [email protected]; Mingkai Hu <[email protected]>;
> [email protected]; [email protected]
> Subject: Re: rtc ds3232 call trace in kernel
>
> 2016-04-19 11:36 GMT+09:00 Qianyu Gong <[email protected]>:
> >
> >> -----Original Message-----
> >> From: Akinobu Mita [mailto:[email protected]]
> >> Sent: Monday, April 18, 2016 9:02 PM
> >> To: Qianyu Gong <[email protected]>
> >> Cc: [email protected]; Mingkai Hu
> >> <[email protected]>; [email protected];
> >> [email protected]
> >> Subject: Re: rtc ds3232 call trace in kernel
> >>
> >> 2016-04-18 15:15 GMT+09:00 Qianyu Gong <[email protected]>:
> >> > Hi Akinobu,
> >> >
> >> >
> >> >
> >> > I got an rtc call trace when booting 4.6 kernel on our board and I
> >> > found it
> >> >
> >> > was caused by this patch:
> >> >
> >> >
> >> >
> >> > commit fc1dcb0b39dbb10d3290f2fcd6e154670f699166
> >> >
> >> > Author: Akinobu Mita <[email protected]>
> >> >
> >> > Date: Mon Mar 7 00:27:53 2016 +0900
> >> >
> >> >
> >> >
> >> > rtc: ds3232: use rtc->ops_lock to protect alarm operations
> >> >
> >> >
> >> >
> >> > ds3232->mutex is used to protect for alarm operations which
> >> >
> >> > need to access status and control registers.
> >> >
> >> >
> >> >
> >> > But we can use rtc->ops_lock instead. rtc->ops_lock is held
> >> > when most
> >> >
> >> > of rtc_class_ops methods are called, so we only need to
> >> > explicitly
> >> >
> >> > acquire it from irq handler in order to protect form concurrent
> >> >
> >> > accesses.
> >> >
> >> >
> >> >
> >> > Signed-off-by: Akinobu Mita <[email protected]>
> >> >
> >> > Signed-off-by: Alexandre Belloni
> >> > <[email protected]
> >> >
> >> >
> >> >
> >> > The problem is that rtc->ops_lock would be accessed in ds3232_irq()
> >> >
> >> > without being initialized as rtc_device_register() is called too late.
> >>
> >> You have already identified the root cause of this issue.
> >>
> >> > As I’m not familiar with rtc things, could I just revert the patch
> >> > or you already
> >> >
> >> > have a solution to this problem? Thanks in advance.
> >>
> >> Could you check if the problem is resolved by moving the call of
> >> devm_rtc_device_register() from the end of ds3232_probe() to just
> >> before registering irq handler?
> >
> > Yes. It works(no call trace now).
>
> Thanks for testing. Do you mind submitting your patch to rtc-
> [email protected] ?
No problem.:)
Regards,
Qianyu