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libkrun: report the net worker's rx stall upstream #1180
Description
Our fork nixidae/libkrun carries a fix (87716f7b) that upstream libkrun does not have. User decides whether to report it to libkrun/libkrun.
The bug, in src/devices/src/virtio/net/worker/unix.rs:
- When the guest's rx queue is full, the worker defers a frame and turns rx notifications off.
- The guest then refills its queue without a kick.
- The backend socket is edge-triggered, so nothing wakes the worker. Rx stops for good.
Queue::enable_notificationreturns true when buffers arrived in between. The old code ignores that answer. The fix re-arms and loops while it returns true.
Evidence (passt uplink, sustained iperf3 to the guest):
- libkrun's socket held 211 KB unread, passt's 24 KB.
- The guest showed no drops, free rx buffers, and its last rx 674 s earlier.
- 2 of 6 by-hand runs stalled before the fix, 0 of 8 after.
Assisted-By: Claude Opus 5.5
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