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

From: Wolfram Sang
Date: Sat Jul 25 2020 - 06:18:24 EST

> 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?

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