Re: [PATCH] USB: ehci: drop workaround for forced irq threading

[Alan Stern]

On Mon, Mar 22, 2021 at 12:12:49PM +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.
> 
> 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 forced
> threading ("threadirqs").

What happens on RT systems?  Are they smart enough to avoid the whole 
problem by enabling interrupts during _all_ callbacks?

Alan Stern