Re: [Qemu-block] [Qemu-devel] [PATCH 0/3] ahci: fix completion race condition

[Bruce Rogers]

>>> On 5/30/2018 at 6:43 PM, John Snow <address@hidden> wrote:
> Commit d759c951f changed the main thread lock release/reacquisition,
> and in so doing apparently jostled loose a race condition in the AHCI
> code.
> 
> Patch 2 should be sufficient to fix this, and patches 1 and 3 are just
> little trivial fixes.
> 
> This might be sufficient to fix the bug as reported at
> https://bugs.launchpad.net/qemu/+bug/1769189 
> but the nature of the timing changes make it difficult to confirm,
> so I am posting this patchset for the reporters to help test.
> 
> John Snow (3):
>   ahci: trim signatures on raise/lower
>   ahci: fix PxCI register race
>   ahci: don't schedule unnecessary BH
> 
>  hw/ide/ahci.c | 24 +++++++++++‑‑‑‑‑‑‑‑‑‑‑‑‑
>  1 file changed, 11 insertions(+), 13 deletions(‑)
> 
> ‑‑ 
> 2.14.3

In my case, I applied these 3 patches on top of v2.12 qemu under which
I can fairly reliably reproduce Windows10 disk delays. With these patches,
after quite a number of attempts, I no longer can reproduce the failure
case, so from my perspective it solves the issue.

Thanks!

Bruce