44  * acquired some snapshot (e) of the global epoch value (e_g) and set an active
46  * For example, assume an initial e_g value of 1, e value of 0 and active value
51  *   active = 1
54  * Any serialized reads may observe e = 0 or e = 1 with active = 0, or e = 0 or
55  * e = 1 with active = 1. The e_g value can only go from 1 to 2 if every thread
58  * critical sections (referred to as "active" threads from here on) would have
86  * still be accessed at e_g as threads are "active" at the same time
93  * e_g-1 were still active, then we would never increment to e_g+1 (active != 0
97  * (since it is valid for active threads to be at e_g and threads at e_g still
100  * However, at e_g+2, all active threads must be either at e_g+1 or e_g+2.
102  * hazardous references to e_g, no active threads are at e_g or e_g-1. This
107  *   1) Active threads will always have a value of e_g or e_g-1.
113  * Last but not least, if we are at e_g+2, then no active thread is at e_g
169 	 * If no other active bucket exists, then the record will go  in CK_STACK_CONTAINER()
281 	record->active = 0;  in ck_epoch_register()
303 	record->active = 0;  in ck_epoch_unregister()
337 		unsigned int state, active;  in ck_epoch_scan()  local
347 		active = ck_pr_load_uint(&cr->active);  in ck_epoch_scan()
348 		*af |= active;  in ck_epoch_scan()
350 		if (active != 0 && ck_pr_load_uint(&cr->epoch) != epoch)  in ck_epoch_scan()
430 	bool active;  in ck_epoch_synchronize_wait()  local
453 		while (cr = ck_epoch_scan(global, cr, delta, &active),  in ck_epoch_synchronize_wait()
491 		if (active == false)  in ck_epoch_synchronize_wait()
499 		 * If we can guarantee there will only be one active barrier or  in ck_epoch_synchronize_wait()
508 		/* Order subsequent thread active checks. */  in ck_epoch_synchronize_wait()
568 	bool active;  in ck_epoch_poll_deferred()  local
581 	 * There may or may not be active threads which observed epoch - 1.  in ck_epoch_poll_deferred()
583 	 * no active threads which observed epoch - 2.  in ck_epoch_poll_deferred()
591 	cr = ck_epoch_scan(global, cr, epoch, &active);  in ck_epoch_poll_deferred()
596 	if (active == false) {  in ck_epoch_poll_deferred()
605 	 * If an active thread exists, rely on epoch observation.  in ck_epoch_poll_deferred()
607 	 * All the active threads entered the epoch section during  in ck_epoch_poll_deferred()