Re: [PATCH] i2c: iproc: fix race between client unreg and isr

[Rayagonda Kokatanur]

On Sat, Jul 25, 2020 at 3:48 PM Wolfram Sang <wsa@xxxxxxxxxx> wrote:
>
>
> > I think the following sequence needs to be implemented to make this
> > safe, i.e., after 'synchronize_irq', no further slave interrupt will be
> > fired.
> >
> > In 'bcm_iproc_i2c_unreg_slave':
> >
> > 1. Set an atomic variable 'unreg_slave' (I'm bad in names so please come
> > up with a better name than this)
> >
> > 2. Disable all slave interrupts
> >
> > 3. synchronize_irq
> >
> > 4. Set slave to NULL
> >
> > 5. Erase slave addresses
>
> What about this in unreg_slave?
>
> 1. disable_irq()
>         This includes synchronize_irq() and avoids the race. Because irq
>         will be masked at interrupt controller level, interrupts coming
>         in at the I2C IP core level should still be pending once we
>         reenable the irq.
>
> 2. disable all slave interrupts
>
> 3. enable_irq()
>
> 4. clean up the rest (pointer, address)
>
> Or am I overlooking something?

This sequence will take care of all cases.

@Dhananjay Phadke is it possible to verify this from your side once.

Best regards,
Raaygonda