Messages in this thread | | | Date | Mon, 2 Nov 2015 20:38:20 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [v4.1.10-rt10][PATCH 1/2] genirq: introduce new generic_handle_irq_rt_wa() api |
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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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