The thrift layer started partially having admission control
after commit ef1de114f0,
but code inspection suggests that it might cause use-after-free
in a few cases, when a permit is obtained more than once per
handling - due to the fact that some functions tail-called other
functions, which also obtain a permit.
These extraneous permits are not taken anyore.
Tests: "please trust me" + cassandra-stress in thrift mode
Message-Id: <ac5d711288b22c5fed566937722cceeabc234e16.1639394937.git.sarna@scylladb.com>