vmm: Avoid deadlock from waiting on paused device worker threads #6293
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rbradford
approved these changes
Mar 13, 2024
vmm/src/device_manager.rs
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| @@ -4977,6 +4977,10 @@ impl BusDevice for DeviceManager { | |||
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| impl Drop for DeviceManager { | |||
| fn drop(&mut self) { | |||
| // Wake up the DeviceManager threads (mainly virtio device workers), | |||
| // to avoid deadlock on waiting for paused/parked worker threads. | |||
| self.resume().ok(); | |||
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lgtm - but would it not be better to log the error here?
A deadlock can happen from the destination VM of live upgrade or migration due to waiting on paused device worker threads. For example, when a serialization error happens after the `DeviceManager` struct is restored (where all virtio device worker threads are spawned but in paused/parked state), a deadlock will happen from `DeviceManager::drop()`, as it blocks for waiting worker threads to join. This patch ensures that we wake up all device (mostly virtio) worker threads before we block for them to join. Signed-off-by: Bo Chen <chen.bo@intel.com>
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A deadlock can happen from the destination VM of live upgrade or migration due to waiting on paused device worker threads. For example, when a serialization error happens after the
DeviceManagerstruct is restored (where all virtio device worker threads are spawned but in paused/parked state), a deadlock will happen fromDeviceManager::drop(), as it blocks for waiting worker threads to join.This patch ensures that we wake up all device (mostly virtio) worker threads before we block for them to join.