Exchange Nodes in a linked list

exchange_nodes.c

/* Exchange places of nodes after, the nodes passed in.*/
exchange(struct node *u, struct node *v) {
  struct node *x, *y;
  x = u->next;
  u->next = u->next->next;
  
  y = v->next;
  v->next = v->next->next;
  
  y->next = u->next;
  u->next = y;

  x->next = v->next;
  v->next = x;
}

struct node {
  int key;
  struct node *next;
}