16 	struct optimistic_spin_node *next, *prev;  member
45  * Get a stable @node->next pointer, either for unlock() or unqueue() purposes.
72 		 * We must xchg() the @node->next value, because if we were to  in osq_wait_next()
74 		 * @node->next might complete Step-A and think its @prev is  in osq_wait_next()
79 		 * wait for a new @node->next from its Step-C.  in osq_wait_next()
81 		if (node->next) {  in osq_wait_next()
82 			struct optimistic_spin_node *next;  in osq_wait_next()  local
84 			next = xchg(&node->next, NULL);  in osq_wait_next()
85 			if (next)  in osq_wait_next()
86 				return next;  in osq_wait_next()
96 	struct optimistic_spin_node *prev, *next;  in osq_lock()  local
101 	node->next = NULL;  in osq_lock()
122 	 * prev->next = node		next->prev = prev // unqueue-C  in osq_lock()
124 	 * Here 'node->prev' and 'next->prev' are the same variable and we need  in osq_lock()
129 	WRITE_ONCE(prev->next, node);  in osq_lock()
154 	 * Undo our @prev->next assignment; this will make @prev's  in osq_lock()
155 	 * unlock()/unqueue() wait for a next pointer since @lock points to us  in osq_lock()
164 		if (data_race(prev->next) == node &&  in osq_lock()
165 		    cmpxchg(&prev->next, node, NULL) == node)  in osq_lock()
186 	 * Step - B -- stabilize @next  in osq_lock()
188 	 * Similar to unlock(), wait for @node->next or move @lock from @node  in osq_lock()
192 	next = osq_wait_next(lock, node, prev->cpu);  in osq_lock()
193 	if (!next)  in osq_lock()
199 	 * @prev is stable because its still waiting for a new @prev->next  in osq_lock()
200 	 * pointer, @next is stable because our @node->next pointer is NULL and  in osq_lock()
204 	WRITE_ONCE(next->prev, prev);  in osq_lock()
205 	WRITE_ONCE(prev->next, next);  in osq_lock()
212 	struct optimistic_spin_node *node, *next;  in osq_unlock()  local
225 	next = xchg(&node->next, NULL);  in osq_unlock()
226 	if (next) {  in osq_unlock()
227 		WRITE_ONCE(next->locked, 1);  in osq_unlock()
231 	next = osq_wait_next(lock, node, OSQ_UNLOCKED_VAL);  in osq_unlock()
232 	if (next)  in osq_unlock()
233 		WRITE_ONCE(next->locked, 1);  in osq_unlock()