kernel: ublk: make sure ubq->canceling is set when queue is frozen

In the Linux kernel, the following vulnerability has been resolved: ublk: make sure ubq-canceling is set when queue is frozen Now ublk driver depends on ubq-canceling for deciding if the request can be dispatched via uringcmd & iouringcmdcompleteintask. Once ubq-canceling is set, the uringcmd can...