Re: [Xen-devel] [PATCH] block: xen-blkback: don't get/put blkif ref for each queue

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Sep 26, 2016 at 03:36:24PM +0800, Bob Liu wrote:
> xen_blkif_get/put() for each queue is useless, and introduces a bug:
> 
> If there is I/O inflight when removing device, xen_blkif_disconnect() will
> return -EBUSY and xen_blkif_put() not be called.
> Which means the references are leaked, then even if I/O completed, the
> xen_blkif_put() won't call xen_blkif_deferred_free() to free resources 
> anymore.
> 
> Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  drivers/block/xen-blkback/xenbus.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/block/xen-blkback/xenbus.c 
> b/drivers/block/xen-blkback/xenbus.c
> index 3cc6d1d..2e1bb6d 100644
> --- a/drivers/block/xen-blkback/xenbus.c
> +++ b/drivers/block/xen-blkback/xenbus.c
> @@ -159,7 +159,6 @@ static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
>               init_waitqueue_head(&ring->shutdown_wq);
>               ring->blkif = blkif;
>               ring->st_print = jiffies;
> -             xen_blkif_get(blkif);
>       }
>  
>       return 0;
> @@ -296,7 +295,6 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
>               BUG_ON(ring->free_pages_num != 0);
>               BUG_ON(ring->persistent_gnt_c != 0);
>               WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
> -             xen_blkif_put(blkif);
>       }
>       blkif->nr_ring_pages = 0;
>       /*
> -- 
> 1.7.10.4
> 

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