Re: [PATCHv3 4/4] nvme/pci: Poll threaded completions

[Daniel Wagner <dwagner@suse.de>]

Hi Keith,

On Tue, Dec 10, 2019 at 02:56:22AM +0900, Keith Busch wrote:
> Poll for new completions in the nvme irq thread as long as it continues
> to observe new ones are available.
> 
> We need to ensure other irq threads affinitized to the same CPU will
> get a chance to run, so exit polling if we wrap the completion queue.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/nvme/host/pci.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 28e08c5ab412..487c6b3858fe 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1011,38 +1011,40 @@ static inline int nvme_process_cq(struct nvme_queue *nvmeq, u16 *start,
>  	return found;
>  }
>  
> -static irqreturn_t nvme_irq(int irq, void *data)
> +static int nvme_irq(int irq, void *data)
>  {
>  	struct nvme_queue *nvmeq = data;
> -	irqreturn_t ret = IRQ_NONE;
>  	u16 start, end;
> +	int found;
>  
>  	/*
>  	 * The rmb/wmb pair ensures we see all updates from a previous run of
>  	 * the irq handler, even if that was on another CPU.
>  	 */
>  	rmb();
> -	nvme_process_cq(nvmeq, &start, &end, -1);
> +	found = nvme_process_cq(nvmeq, &start, &end, -1);
>  	wmb();

Are the memory barries still at the right place after this change?

Thanks,
Daniel

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