[PATCH v2] i2c: rk3x: fix potential spinlock recursion on poll

[Dragan Simic]

On 2023-12-07 10:25, Jensen Huang wrote:
> On Thu, Dec 7, 2023 at 4:37 PM Dragan Simic <dsimic at manjaro.org> wrote:
>> 
>> On 2023-12-07 09:21, Jensen Huang wrote:
>> > Possible deadlock scenario (on reboot):
>> > rk3x_i2c_xfer_common(polling)
>> >     -> rk3x_i2c_wait_xfer_poll()
>> >         -> rk3x_i2c_irq(0, i2c);
>> >             --> spin_lock(&i2c->lock);
>> >             ...
>> >         <rk3x i2c interrupt>
>> >         -> rk3x_i2c_irq(0, i2c);
>> >             --> spin_lock(&i2c->lock); (deadlock here)
>> >
>> > Store the IRQ number and disable/enable it around the polling transfer.
>> > This patch has been tested on NanoPC-T4.
>> 
>> In case you haven't already seen the related discussion linked below,
>> please have a look.  I also added more people to the list of 
>> recipients,
>> in an attempt to make everyone aware of the different approaches to
>> solving this issue.
>> 
>> https://lore.kernel.org/all/655177f4.050a0220.d85c9.3ba0@mx.google.com/T/#m6fc9c214452fec6681843e7f455978c35c6f6c8b
> 
> Thank you for providing the information. I hadn't seen this link 
> before.
> After carefully looking into the related discussion, it appears that
> Dmitry Osipenko is already working on a suitable patch. To avoid 
> duplication
> or conflicts, my patch can be discarded.

Thank you for responding so quickly.  Perhaps it would be best to hear 
from Dmitry as well, before discarding anything.  It's been a while 
since Dmitry wrote about working on the patch, so he might have 
abandoned it.