[v2] mirror: Fix hang (operation waiting for itself/circular dependency)

[PATCH v2 0/2] mirror: Fix hang (operation waiting for itself/circular dependency)

Kevin Wolf posted 2 patches 4 years, 1 month ago

Diff against v1
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git fetch https://github.com/patchew-project/qemu tags/patchew/20200326153628.4869-1-kwolf@redhat.com

Maintainers: Max Reitz <mreitz@redhat.com>, John Snow <jsnow@redhat.com>, Kevin Wolf <kwolf@redhat.com>

block/mirror.c | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)

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[PATCH v2 0/2] mirror: Fix hang (operation waiting for itself/circular dependency)

Posted by Kevin Wolf 4 years, 1 month ago

The recent fix didn't actually fix the whole problem. Operations can't
only wait for themselves, but we can also end up with circular
dependencies like two operations waiting for each other to complete.

This reverts the first fix and implements another approach.

v2:
- Mark active mirror operations as in-flight, too

Kevin Wolf (2):
  Revert "mirror: Don't let an operation wait for itself"
  mirror: Wait only for in-flight operations

 block/mirror.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

-- 
2.20.1

Re: [PATCH v2 0/2] mirror: Fix hang (operation waiting for itself/circular dependency)

Posted by Eric Blake 4 years, 1 month ago

On 3/26/20 10:36 AM, Kevin Wolf wrote:
> The recent fix didn't actually fix the whole problem. Operations can't
> only wait for themselves, but we can also end up with circular
> dependencies like two operations waiting for each other to complete.
> 
> This reverts the first fix and implements another approach.
> 
> v2:
> - Mark active mirror operations as in-flight, too
> 
> Kevin Wolf (2):
>    Revert "mirror: Don't let an operation wait for itself"
>    mirror: Wait only for in-flight operations

Series:
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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