ublk_drv: do not add a re-issued request aborted previously to ioucmd's task_work
In ublk_queue_rq(), Assume current request is a re-issued request aborted previously in monitor_work because the ubq_daemon(ioucmd's task) is PF_EXITING. For this request, we cannot call io_uring_cmd_complete_in_task() anymore because at that moment io_uring context may be freed in case that no inflight ioucmd exists. Otherwise, we may cause null-deref in ctx->fallback_work. Add a check on UBLK_IO_FLAG_ABORTED to prevent the above situation. This check is safe and makes sense. Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request (releasing the tag). Then the request is restarted(allocating the tag) and we are here. Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED guarantees that here is a re-issued request aborted previously. Suggested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20220815023633.259825-4-ZiyangZhang@linux.alibaba.comSigned-off-by: Jens Axboe <axboe@kernel.dk>
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