mirror of
https://github.com/moby/moby.git
synced 2022-11-09 12:21:53 -05:00
af433dd200
As pointed out by Tonis, there's a race between ReleaseRWLayer() and GetRWLayer(): ``` ----- goroutine 1 ----- ----- goroutine 2 ----- ReleaseRWLayer() m := ls.mounts[l.Name()] ... m.deleteReference(l) m.hasReferences() ... GetRWLayer() ... mount := ls.mounts[id] ls.driver.Remove(m.mountID) ls.store.RemoveMount(m.name) return mount.getReference() delete(ls.mounts, m.Name()) ----------------------- ----------------------- ``` When something like this happens, GetRWLayer will return an RWLayer without a storage. Oops. There might be more races like this, and it seems the best solution is to lock by layer id/name by using pkg/locker. With this in place, name collision could not happen, so remove the part of previous commit that protected against it in CreateRWLayer (temporary nil assigmment and associated rollback). So, now we have * layerStore.mountL sync.Mutex to protect layerStore.mount map[] (against concurrent access); * mountedLayer's embedded `sync.Mutex` to protect its references map[]; * layerStore.layerL (which I haven't touched); * per-id locker, to avoid name conflicts and concurrent operations on the same rw layer. The whole rig seems to look more readable now (mutexes use is straightforward, no nested locks). Reported-by: Tonis Tiigi <tonistiigi@gmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> |
||
|---|---|---|
| .. | ||
| empty.go | ||
| empty_test.go | ||
| filestore.go | ||
| filestore_test.go | ||
| filestore_unix.go | ||
| filestore_windows.go | ||
| layer.go | ||
| layer_store.go | ||
| layer_store_windows.go | ||
| layer_test.go | ||
| layer_unix.go | ||
| layer_unix_test.go | ||
| layer_windows.go | ||
| migration.go | ||
| migration_test.go | ||
| mount_test.go | ||
| mounted_layer.go | ||
| ro_layer.go | ||
| ro_layer_windows.go | ||