Messages in this thread | | | Date | Fri, 12 Oct 2012 14:46:18 +0200 (CEST) | From | Thomas Gleixner <> | Subject | RE: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support with irq thread |
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On Fri, 12 Oct 2012, Liu, Chuansheng wrote: > > -----Original Message----- > > From: Thomas Gleixner [mailto:tglx@linutronix.de] > > Sent: Friday, October 12, 2012 8:32 PM > > To: Liu, Chuansheng > > Cc: linux-kernel@vger.kernel.org > > Subject: Re: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support with irq > > thread > > > > On Fri, 12 Oct 2012, Chuansheng Liu wrote: > > > > > > In our system, there is one edge interrupt, and we want it to be > > > irq thread with IRQS_ONESHOT, and found in handle_edge_irq(), > > > even with IRQS_ONESHOT, the irq is still unmasked without care of > > > flag IRQS_ONESHOT. > > > > > > It causes IRQS_ONESHOT can not work well for edge interrupt, but also > > > after the irq thread finished with flag IRQS_ONESHOT, the irq will be > > > possible to be unmasked again, it should be messing mask/unmask logic. > > > > This is just wrong. By masking edge interrupts you will run into > > situations where you will lose interrupts. > > > > Can you please explain, why you want to mask your edge interrupt?
> When I request_irq with irq thread handler and flag IRQS_ONESHOT, if > do not mask the edge interrupt, the primary handler and irq thread > maybe run at the same time, and in my real case it causes spin > deadlock.
Then your code is simply wrong and you need to fix it instead of hacking a workaround into the core code. Locking is not that hard.
> You means it is not right with IRQS_ONESHOT for edge interrupt?
It's wrong. Simnply because you can lose interrupts.
interrupt raised handle_edge_irq() mask_ack_irq() handle_event() wake irq thread reti
irq thread runs handle device interrupt() <--- device issues edge irq unmask_irq()
This interrupt is not delivered. So your device stops working. Not what you want, right?
Thanks,
tglx
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