• Sebastian Andrzej Siewior's avatar
    drm/i915/gt: Use spin_lock_irq() instead of local_irq_disable() + spin_lock() · 922f723f
    Sebastian Andrzej Siewior authored
    
    
    execlists_dequeue() is invoked from a function which uses
    local_irq_disable() to disable interrupts so the spin_lock() behaves
    like spin_lock_irq().
    This breaks PREEMPT_RT because local_irq_disable() + spin_lock() is not
    the same as spin_lock_irq().
    
    execlists_dequeue_irq() and execlists_dequeue() has each one caller
    only. If intel_engine_cs::active::lock is acquired and released with the
    _irq suffix then it behaves almost as if execlists_dequeue() would be
    invoked with disabled interrupts. The difference is the last part of the
    function which is then invoked with enabled interrupts.
    I can't tell if this makes a difference. From looking at it, it might
    work to move the last unlock at the end of the function as I didn't find
    anything that would acquire the lock again.
    Reported-by: default avatarClark Williams <williams@redhat.com>
    Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
    922f723f