On Wed, Mar 17 2021 at 15:48, Sebastian Andrzej Siewior wrote: > On 2021-03-17 15:38:52 [+0100], Thomas Gleixner wrote: >> thread(irq_A) >> irq_handler(A) >> spin_lock(&foo->lock); >> >> interrupt(irq_B) >> irq_handler(B) >> spin_lock(&foo->lock); > > It will not because both threads will wake_up(thread). It is an issue if > - if &foo->lock is shared between a hrtimer and threaded-IRQ > - if &foo->lock is shared between a non-threaded and thread-IRQ > - if &foo->lock is shared between a printk() in hardirq context and > thread-IRQ as I learned today.
That's the point and it's entirely clear from the above: A is thread context and B is hard interrupt context and if the lock is shared then it's busted. Otherwise we would not have this discussion at all.
