+ u32 free = 0;
+ while (!clib_atomic_cmp_and_swap_acq_relax_n (&(*p)->lock, &free, 1, 0))
+ {
+ /* atomic load limits number of compare_exchange executions */
+ while (clib_atomic_load_relax_n (&(*p)->lock))
+ CLIB_PAUSE ();
+ /* on failure, compare_exchange writes (*p)->lock into free */
+ free = 0;
+ }