[PATCH 01/14] ubd: refactor the interrupt handler

[Anton Ivanov]

On 31/05/2024 08:47, Christoph Hellwig wrote:
> Instead of a separate handler function that leaves no work in the
> interrupt hanler itself, split out a per-request end I/O helper and
> clean up the coding style and variable naming while we're at it.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> Reviewed-by: Martin K. Petersen <martin.petersen at oracle.com>
> ---
>   arch/um/drivers/ubd_kern.c | 49 ++++++++++++++------------------------
>   1 file changed, 18 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
> index ef805eaa9e013d..0c9542d58c01b7 100644
> --- a/arch/um/drivers/ubd_kern.c
> +++ b/arch/um/drivers/ubd_kern.c
> @@ -447,43 +447,30 @@ static int bulk_req_safe_read(
>   	return n;
>   }
>   
> -/* Called without dev->lock held, and only in interrupt context. */
> -static void ubd_handler(void)
> +static void ubd_end_request(struct io_thread_req *io_req)
>   {
> -	int n;
> -	int count;
> -
> -	while(1){
> -		n = bulk_req_safe_read(
> -			thread_fd,
> -			irq_req_buffer,
> -			&irq_remainder,
> -			&irq_remainder_size,
> -			UBD_REQ_BUFFER_SIZE
> -		);
> -		if (n < 0) {
> -			if(n == -EAGAIN)
> -				break;
> -			printk(KERN_ERR "spurious interrupt in ubd_handler, "
> -			       "err = %d\n", -n);
> -			return;
> -		}
> -		for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
> -			struct io_thread_req *io_req = (*irq_req_buffer)[count];
> -
> -			if ((io_req->error == BLK_STS_NOTSUPP) && (req_op(io_req->req) == REQ_OP_DISCARD)) {
> -				blk_queue_max_discard_sectors(io_req->req->q, 0);
> -				blk_queue_max_write_zeroes_sectors(io_req->req->q, 0);
> -			}
> -			blk_mq_end_request(io_req->req, io_req->error);
> -			kfree(io_req);
> -		}
> +	if (io_req->error == BLK_STS_NOTSUPP &&
> +	    req_op(io_req->req) == REQ_OP_DISCARD) {
> +		blk_queue_max_discard_sectors(io_req->req->q, 0);
> +		blk_queue_max_write_zeroes_sectors(io_req->req->q, 0);
>   	}
> +	blk_mq_end_request(io_req->req, io_req->error);
> +	kfree(io_req);
>   }
>   
>   static irqreturn_t ubd_intr(int irq, void *dev)
>   {
> -	ubd_handler();
> +	int len, i;
> +
> +	while ((len = bulk_req_safe_read(thread_fd, irq_req_buffer,
> +			&irq_remainder, &irq_remainder_size,
> +			UBD_REQ_BUFFER_SIZE)) >= 0) {
> +		for (i = 0; i < len / sizeof(struct io_thread_req *); i++)
> +			ubd_end_request((*irq_req_buffer)[i]);
> +	}
> +
> +	if (len < 0 && len != -EAGAIN)
> +		pr_err("spurious interrupt in %s, err = %d\n", __func__, len);
>   	return IRQ_HANDLED;
>   }
>   
Acked-By: Anton Ivanov <anton.ivanov at cambridgegreys.com>
-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/