TTY之struct tty

struct tty_buffer {  union {   struct tty_buffer *next;   struct llist_node free;  };  int used;  int size;  int commit;  int read;  int flags;  /* Data points here */  unsigned long data[0]; };   struct tty_bufhead {  struct tty_buffer *head; /* Queue head */  struct work_struct work;  struct mutex    lock;  atomic_t    priority;  struct tty_buffer sentinel;  struct llist_head free;  /* Free queue head */  atomic_t    mem_used;    /* In-use buffers excluding free list */  int     mem_limit;  struct tty_buffer *tail; /* Active buffer */ };