kernel: net/sched: sch_api: fix xa_insert() error path in tcf_block_get_ext()

In the Linux kernel, the following vulnerability has been resolved: net/sched: schapi: fix xainsert error path in tcfblockgetext This command: $ tc qdisc replace dev eth0 ingressblock 1 egressblock 1 clsact Error: block dev insert failed: -EBUSY. fails because user space requests the same block...