Re: [Qemu-devel] [Qemu-block] [PATCH] bdrv_inc_in_flight and bdrv_dec_in_flight:

[Manos Pitsidianakis]

On Sat, Jun 10, 2017 at 03:04:10PM +0800, Zhengui Li wrote:
> Avoid empty pointer access if the bs is NULL.

Looks like most (if not all) of the places these are called dereference 
bs anyway. Can it ever be NULL? Perhaps a check for each of those case 
(if any) would be a better idea.

> Signed-off-by: Zhengui Li <address@hidden>
> ---
> block/io.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/block/io.c b/block/io.c
> index ed31810..b12d7cf 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -492,7 +492,9 @@ static bool tracked_request_overlaps(BdrvTrackedRequest 
> *req,
>
> void bdrv_inc_in_flight(BlockDriverState *bs)
> {
> -    atomic_inc(&bs->in_flight);
> +    if (bs) {
> +        atomic_inc(&bs->in_flight);
> +    }
> }
>
> static void dummy_bh_cb(void *opaque)
> @@ -508,8 +510,10 @@ void bdrv_wakeup(BlockDriverState *bs)
>
> void bdrv_dec_in_flight(BlockDriverState *bs)
> {
> -    atomic_dec(&bs->in_flight);
> -    bdrv_wakeup(bs);
> +    if (bs) {
> +        atomic_dec(&bs->in_flight);
> +        bdrv_wakeup(bs);
> +    }
> }
>
> static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
> --
> 1.8.3.1

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