Re: [Qemu-block] [PATCH v3 28/44] block: Fix pending requests check in bdrv_append()

2017-10-04 Thread Alberto Garcia 
On Tue 28 Feb 2017 01:54:13 PM CET, Kevin Wolf wrote:
> bdrv_append() cares about isolation of the node that it modifies, but
> not about activity in some subtree below it. Instead of using the
> recursive bdrv_requests_pending(), directly check bs->in_flight, which
> considers only the node in question.
>
> Signed-off-by: Kevin Wolf 
> Reviewed-by: Max Reitz 
> ---
>  block.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block.c b/block.c
> index 9e538a5..5189c7c 100644
> --- a/block.c
> +++ b/block.c
> @@ -2897,8 +2897,8 @@ static void change_parent_backing_link(BlockDriverState 
> *from,
>   */
>  void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top)
>  {
> -assert(!bdrv_requests_pending(bs_top));
> -assert(!bdrv_requests_pending(bs_new));
> +assert(!atomic_read(&bs_top->in_flight));
> +assert(!atomic_read(&bs_new->in_flight));
>  
>  bdrv_ref(bs_top);

I don't know if there's still any maintenance on the v2.8.x branch, but
I can make v2.8.1.1 crash easily because of this failing assertion.
Applying this patch fixes the issue.

I can provide more details if needed.

Regards,

Berto

[Qemu-block] [PATCH v3 28/44] block: Fix pending requests check in bdrv_append()

2017-02-28 Thread Kevin Wolf 
bdrv_append() cares about isolation of the node that it modifies, but
not about activity in some subtree below it. Instead of using the
recursive bdrv_requests_pending(), directly check bs->in_flight, which
considers only the node in question.

Signed-off-by: Kevin Wolf 
Reviewed-by: Max Reitz 
---
 block.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index 9e538a5..5189c7c 100644
--- a/block.c
+++ b/block.c
@@ -2897,8 +2897,8 @@ static void change_parent_backing_link(BlockDriverState 
*from,
  */
 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top)
 {
-assert(!bdrv_requests_pending(bs_top));
-assert(!bdrv_requests_pending(bs_new));
+assert(!atomic_read(&bs_top->in_flight));
+assert(!atomic_read(&bs_new->in_flight));
 
 bdrv_ref(bs_top);
 
-- 
1.8.3.1