On Mon, Mar 22, 2021 at 12:10:36PM +0100, Johan Hovold wrote:

Force-threaded interrupt handlers used to run with interrupts enabled,
something which could lead to deadlocks in case a threaded handler
shared a lock with code running in hard interrupt context (e.g. timer
callbacks) and did not explicitly disable interrupts.

This was specifically the case for serial drivers that take the port
lock in their console write path as printk can be called from hard
interrupt context also with forced threading ("threadirqs").

Since commit 81e2073c175b ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers always run with interrupts
disabled on non-RT so that drivers no longer need to do handle this.

So we're breaking RT knowingly here? If this is the case I'm not happy
with your change. (And if RT is not affected a different wording would
be good.)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |