On 3/18/21 9:27 AM, Lars-Peter Clausen wrote:
On 3/18/21 9:07 AM, Pavel Andrianov wrote:
Hi,
berlin2_adc_probe [1] registers two interrupt handlers:
berlin2_adc_irq [2]
and berlin2_adc_tsen_irq [3]. The interrupt handlers operate with the
same data, for example, modify
priv->data with different masks:
priv->data &= BERLIN2_SM_ADC_MASK;
and
priv->data &= BERLIN2_SM_TSEN_MASK;
If the two interrupt handlers are executed simultaneously, a
potential data race takes place. So, the question is if the situation
is possible. For example, in the case of the handlers are executed on
different CPU cores.
Best regards,
Pavel
[1]
https://elixir.bootlin.com/linux/latest/source/drivers/iio/adc/berlin2-adc.c#L283
[2]
https://elixir.bootlin.com/linux/latest/source/drivers/iio/adc/berlin2-adc.c#L239
[3]
https://elixir.bootlin.com/linux/latest/source/drivers/iio/adc/berlin2-adc.c#L259
Looking at the code there are two functions. berlin2_adc_tsen_read()
and berlin2_adc_read(). These two function are take the same mutex and
can not run concurrently. At the beginning of the protected section
the corresponding interrupt for that function is enabled and at the
end disabled. So at least if the hardware works correctly those two
interrupts will never fire at the same time.
Now, if the hardware misbehaves the two interrupts could still fire at
the same time.
- Lars
Actually thinking a bit more about this the interrupt could still fire
after it has been disabled since there is no synchronization between the
disable and the interrupt handler. And the handler might be queued on
one CPU, while the disable is running on another CPU.
