On Mon, 2 Nov 2015, Grygorii Strashko wrote:
> Now in kernel below code pattern is used by many drivers:
> static irqreturn_t driver_xx_hw_irq_handler(int irq, void *arg)
> {
> <read IRQ status register>
> <perform HW specific operations>
>
> for (<each set bit in IRQ status register>) {
> <get Linux IRQ number>
> generic_handle_irq(<Linux IRQ number>);
> |- handle_simple_irq()
> |-or- handle_level_irq()
> |-or- handle_edge_irq()
> |-handle_irq_event()
> |-handle_irq_event_percpu()
> ===
> "WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150 handle_irq_event_percpu+0x14c/0x174()
> irq 460 handler irq_default_primary_handler+0x0/0x14 enabled interrupts"
> ===
> }
> }
>
> On -RT above code will generate warnings, because driver_xx_hw_irq_handler()
> will be forced threaded (by default) and, as result, generic_handle_irq()
> will be called with IRQs enabled. To W/A this issue generic_handle_irq() can
> be surrounded by raw_spin_lock_irqsave/irqrestore(wa_lock).
>
> Instead of spreading this W/A directly in many drivers this patch
> introduces -RT specific version of generic_handle_irq() API -
> generic_handle_irq_rt_wa(). This new generic_handle_irq_rt_wa() just calls
> generic_handle_irq() surrounded by raw_spin_lock_irqsave/irqrestore().
> If -RT is disabled It will fallback to generic_handle_irq().
Why aren't you simply marking these demultiplex handlers with IRQ_NO_THREAD?
Thanks,
tglx
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