Messages in this thread | | | Date | Fri, 21 Mar 2014 16:11:09 -0400 | From | Matthew Wilcox <> | Subject | Re: A question about NVMe's nvme-irq |
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On Fri, Mar 21, 2014 at 11:29:02AM +0800, liaohengquan1986 wrote: > hello, > There is question confusing me recently. In the function of nvme-irq as belows: > static irqreturn_t nvme_irq(int irq, void *data) > { > irqreturn_t result; > struct nvme_queue *nvmeq = data; > spin_lock(&nvmeq->q_lock); > nvme_process_cq(nvmeq); > result = nvmeq->cqe_seen ? IRQ_HANDLED : IRQ_NONE; > nvmeq->cqe_seen = 0; > spin_unlock(&nvmeq->q_lock); > return result; > } > If there are two cqes which trigger two irqs, but they are so closed that the first nvme-irq() handles both the cqes( including the second cqe which triggers the second irq), > then the second nvme_process_cq() will find there is no cqe in the CQ and return nvmeq->cqe_seen = 0, and nvme-irq will return IRQ_NONE. > I think maybe this is a bug, because there actually are two irqs, it's not right to return IRQ_NONE, isn't it?
/* If the controller ignores the cq head doorbell and continuously * writes to the queue, it is theoretically possible to wrap around * the queue twice and mistakenly return IRQ_NONE. Linux only * requires that 0.1% of your interrupts are handled, so this isn't * a big problem. */
I should probably update & move that comment, but nevertheless, it applies to your situation too.
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