Re: [PATCH 3/3] ath9k: Fix potential hw interrupt resume during reset

On 2021-09-14 21:25, Linus Lüssing wrote:

From: Linus Lüssing <redacted>

There is a small risk of the ath9k hw interrupts being reenabled in the
following way:

1) ath_reset_internal()
   ...
   -> disable_irq()
      ...
      <- returns

                      2) ath9k_tasklet()
                         ...
                         -> ath9k_hw_resume_interrupts()
                         ...

1) ath_reset_internal() continued:
   -> tasklet_disable(&sc->intr_tq); (= ath9k_tasklet() off)

By first disabling the ath9k interrupt there is a small window
afterwards which allows ath9k hw interrupts being reenabled through
the ath9k_tasklet() before we disable this tasklet in
ath_reset_internal(). Leading to having the ath9k hw interrupts enabled
during the reset, which we should avoid.

I don't see a way in which interrupts can be re-enabled through the
tasklet. disable_irq disables the entire PCI IRQ (not through ath9k hw
registers), and they will only be re-enabled by the corresponding
enable_irq call.

- Felix