Re: [bisected] Re: Module removal-related regression?

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On September 9, 2017 1:17:26 PM PDT, Jakub Kicinski <kubakici@wp.pl> wrote:
>On Sat, 9 Sep 2017 12:55:51 -0700, Dmitry Torokhov wrote:
>> On Sat, Sep 9, 2017 at 12:27 PM, Jakub Kicinski <kubakici@wp.pl>
>wrote:
>> > On Sat, 9 Sep 2017 19:41:21 +0200, Jakub Kicinski wrote:  
>> >> Hi!
>> >>
>> >> I'm having trouble with modules on linux/master.  rmmod succeeds
>but the
>> >> module is still loaded and the refcount goes to 1:
>> >>
>> >> #rmmod nfp; insmod ./src/nfp.ko nfp_pf_netdev=0 ; \
>> >>       /opt/netronome/bin/nfp-hwinfo -n 2  assembly.partno \
>> >>       lsmod | grep nfp; \
>> >>       rmmod nfp; \
>> >>       lsmod | grep nfp
>> >> nfp                   249856  0
>> >> nfp                   200704  1
>> >>
>> >> If I rmmod again the module will be actually unloaded.  The user
>space
>> >> is mostly Ubuntu 14.04.  Has anyone seen this?  I'm trying to
>bisect
>> >> now...  
>> >
>> > Got 'em!
>> >
>> > commit 1455cf8dbfd06aa7651dcfccbadb7a093944ca65 (HEAD,
>refs/bisect/bad)
>> > Author: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>> > Date:   Wed Jul 19 17:24:30 2017 -0700
>> >
>> >     driver core: emit uevents when device is bound to a driver  
>> 
>> Does it happen with all modules or only nfp one?
>> 
>> It seems to work here:
>> 
>> dtor@dtor-glaptop3:~ $ lsmod | grep psmouse
>> psmouse               135168  0
>> dtor@dtor-glaptop3:~ $ sudo rmmod psmouse
>> dtor@dtor-glaptop3:~ $ lsmod | grep psmouse
>> dtor@dtor-glaptop3:~ $ sudo modprobe psmouse
>
>It looks like the driver is actually reloaded.  The driver used to
>return EPROBE_DEFER, but I think it doesn't any more (rebuilding the
>kernel to test that right now).
>
>Could the uevent on unbind tickle Ubuntu 14.04's udev or somehow
>else cause the driver to be loaded again? 

It depends on how silly the udev rules are, but yes, this can definitely happen.


Thanks.

-- 
Dmitry