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google / novm

Experimental KVM-based VMM for containers, written in Go.
Apache License 2.0
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Fix data race of Ram struct and VirtioBufferSet map #35

Closed hamo closed 9 months ago

hamo commented 9 years ago

On my computer, novm still can not work with go 1.4. When trying to debug this issue, go race detector found 2 race conditions.

The first one is Ram struct. And is fixed by commit 6f665f4. This is the output of go race detector:

WARNING: DATA RACE Read by goroutine 16: novmm/machine.(_MsiXDevice).ClearPending() /home/hamo/workspace/novm/src/novmm/machine/msix.go:137 +0xa8 novmm/machine.(_MsiXDevice).SendInterrupt() /home/hamo/workspace/novm/src/novmm/machine/msix.go:355 +0x1b0 novmm/machine.(_VirtioChannel).Interrupt() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:353 +0xe0 novmm/machine.(_VirtioChannel).ProcessOutgoing() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:328 +0x3a5

Previous write by goroutine 18: novmm/machine.(_MsiXDevice).ClearPending() /home/hamo/workspace/novm/src/novmm/machine/msix.go:138 +0x1a3 novmm/machine.(_MsiXDevice).SendInterrupt() /home/hamo/workspace/novm/src/novmm/machine/msix.go:355 +0x1b0 novmm/machine.(_VirtioChannel).Interrupt() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:353 +0xe0 novmm/machine.(_VirtioChannel).ProcessOutgoing() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:328 +0x3a5

Goroutine 16 (running) created at: novmm/machine.(_VirtioChannel).start() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:669 +0xed novmm/machine.(_VirtioDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:829 +0x261 novmm/machine.(_VirtioConsoleDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio_console.go:187 +0x6c novmm/machine.(_Model).CreateDevices() /home/hamo/workspace/novm/src/novmm/machine/state.go:105 +0x1f5 main.main() /home/hamo/workspace/novm/src/novmm/main.go:188 +0x90e

Goroutine 18 (running) created at: novmm/machine.(_VirtioChannel).start() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:669 +0xed novmm/machine.(_VirtioDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:829 +0x261 novmm/machine.(_VirtioConsoleDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio_console.go:187 +0x6c novmm/machine.(_Model).CreateDevices() /home/hamo/workspace/novm/src/novmm/machine/state.go:105 +0x1f5 main.main() /home/hamo/workspace/novm/src/novmm/main.go:188 +0x90e

The second one is VirtioBufferSet map, and it is fixed by commit 7c7595d. Output of go race detector:

WARNING: DATA RACE Write by goroutine 19: runtime.mapassign1() /build/go/src/go-1.4.1/src/runtime/hashmap.go:383 +0x0 novmm/machine.(_VirtioChannel).processOne() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:209 +0x78b novmm/machine.(_VirtioChannel).consumeOne() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:249 +0x10d novmm/machine.(*VirtioChannel).ProcessIncoming() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:287 +0x10f

Previous write by goroutine 18: runtime.mapdelete() /build/go/src/go-1.4.1/src/runtime/hashmap.go:495 +0x0 novmm/machine.(*VirtioChannel).ProcessOutgoing() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:339 +0x408

Goroutine 19 (running) created at: novmm/machine.(_VirtioChannel).start() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:670 +0x107 novmm/machine.(_VirtioDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:829 +0x261 novmm/machine.(_VirtioConsoleDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio_console.go:187 +0x6c novmm/machine.(_Model).CreateDevices() /home/hamo/workspace/novm/src/novmm/machine/state.go:105 +0x1f5 main.main() /home/hamo/workspace/novm/src/novmm/main.go:188 +0x90e

Goroutine 18 (running) created at: novmm/machine.(_VirtioChannel).start() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:669 +0xed novmm/machine.(_VirtioDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio.go:829 +0x261 novmm/machine.(_VirtioConsoleDevice).Attach() /home/hamo/workspace/novm/src/novmm/machine/virtio_console.go:187 +0x6c novmm/machine.(_Model).CreateDevices() /home/hamo/workspace/novm/src/novmm/machine/state.go:105 +0x1f5 main.main() /home/hamo/workspace/novm/src/novmm/main.go:188 +0x90e

Review on Reviewable

amscanne commented 9 years ago

Good catch! I need to remember the intent regarding the virtio outstanding map. I'll update shortly.