vsock: avoid circular references #499
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stefano-garzarella
requested review from
mathieupoirier,
stsquad and
vireshk
as code owners
We have the following circular references found by Li Zebin:
VhostUserBackend ==> VhostUserVsockThread ==> VringEpollHandler
In addition to causing a resource leak, this causes also an error
after we merged commit 38caab2 ("vsock: Don't allow duplicate CIDs").
When the VM reboot or shutdown, the application exits with the
following error:
[ERROR vhost_device_vsock] Could not create backend:
CID already in use by another vsock device
This happened because we have these circular references and
VhostUserVsockThread::drop() is never invoked. So, we don't remove
the cid from the map.
Let's fix this problem by simply removing the reference to
VringEpollHandler from VhostUserVsockThread. In fact, we do not
need to keep the reference for the lifetime of VhostUserVsockThread,
as we only need to add the handlers once.
Let's also rename the fields to follow the current VhostUserDaemon
API.
Closes rust-vmm#438
Reported-by: Li Zebin <cutelizebin@gmail.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
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vireshk
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Oct 25, 2023
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Summary of the PR
We have the following circular references found by Li Zebin:
VhostUserBackend ==> VhostUserVsockThread ==> VringEpollHandler
In addition to causing a resource leak, this causes also an error after we merged commit 38caab2 ("vsock: Don't allow duplicate CIDs"). When the VM reboot or shutdown, the application exits with the following error:
This happened because we have these circular references and VhostUserVsockThread::drop() is never invoked. So, we don't remove the cid from the map.
Let's fix this problem by simply removing the reference to VringEpollHandler from VhostUserVsockThread. In fact, we do not need to keep the reference for the lifetime of VhostUserVsockThread, as we only need to add the handlers once.
Let's also rename the fields to follow the current VhostUserDaemon API.
Closes #438
Reported-by: Li Zebin cutelizebin@gmail.com
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