Add a mutex around the PTM transaction to prevent multiple transactors
Multiple processes try to initiate a PTM transaction, one or all may
fail. This can be reproduced by running two instances of the
following:
$ sudo phc2sys -O 0 -i tsn0 -m
PHC2SYS exits with:
"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
fails
Note: Normally two instance of PHC2SYS will not run, but one process
should not break another.
Fixes: a90ec84837 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.hall@intel.com>
Reviewed-by: Corinna Vinschen <vinschen@redhat.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>