Handle read errors from ctl_fd such as EINTR, EAGAIN and EWOULDBLOCK.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/20200901093758.32293-3-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>