Re: Question about apds990x.ko

[Anton Volkov]

The author of this driver as well as bh1770glc.ko is Samu Onkalo. His 
e-mail that was found as a contact in the module's source is invalid. I 
tried to add him previous time (Question about bh1770glc.ko). The 
message was not delivered then.

On 10.08.2017 18:07, Greg KH wrote:
> On Thu, Aug 10, 2017 at 05:57:30PM +0300, Anton Volkov wrote:
> > Hello.
> >
> > While searching for races in the Linux kernel I've come across
> > "drivers/misc/apds990x.ko" module. Here are questions that I came up with
> > while analyzing results. Lines are given using the info from Linux v4.12.
> >
> > Consider the following case:
> >
> > Thread 1:                      Thread 2:
> > apds990x_suspend
> > apds990x_resume                apds990x_irq
> > -> apds990x_chip_on              if (!pm_runtime_suspended
> >                                                    (chip->client->dev)){
> >     -> apds990x_configure           if (status & APDS990X_ST_AINT) {
> >          chip->again_meas = 1         chip->again_meas = chip->again_next
> >          (apds990x.c: line 571)       (apds990x.c: line 505)
> >                                     }
> >                                    }
> >
> > First question. Is this race feasible from your point of view?
> > Second question. The check for the device suspension status
> > (pm_runtime_suspended()) is present in the interrupt handler, but the
> > functions pm_runtime_set_suspended / pm_runtime_set_active are not used in
> > apds990x_suspend / apds990x_resume respectively. Do you know about any other
> > method being used to make the modification of suspension status?
>
> No idea, sorry.  Maybe the driver authors know?
>
> greg k-h

--
-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@xxxxxxxxx