/*  * Some notes on locking: * *	All the locking woes come from implementing *	threadinterrupt (and threadkill). * *	_threadgetproc()->thread is always a live pointer. *	p->threads, p->ready, and _threadrgrp also contain * 	live thread pointers.  These may only be consulted *	while holding p->lock or _threadrgrp.lock; in procs *	other than p, the pointers are only guaranteed to be live *	while the lock is still being held. * *	Thread structures can only be freed by the proc *	they belong to.  Threads marked with t->inrendez * 	need to be extracted from the _threadrgrp before *	being freed. * *	_threadrgrp.lock cannot be acquired while holding p->lock. */ typedef struct Pqueue	Pqueue;typedef struct Rgrp		Rgrp;typedef struct Tqueue	Tqueue;typedef struct Thread	Thread;typedef struct Execargs	Execargs;typedef struct Proc		Proc; /* must match list in sched.c */typedef enum{	Dead,	Running,	Ready,	Rendezvous,} State;	typedef enum{	Channone,	Chanalt,	Chansend,	Chanrecv,} Chanstate; enum{	RENDHASH = 13,	Printsize = 2048,}; struct Rgrp{	Lock		lock;	Thread	*hash[RENDHASH];}; struct Tqueue		/* Thread queue */{	int		asleep;	Thread	*head;	Thread	**tail;}; struct Thread{	Lock		lock;			/* protects thread data structure */	jmp_buf	sched;		/* for context switches */	int		id;			/* thread id */	int 		grp;			/* thread group */	int		moribund;	/* thread needs to die */	State		state;		/* run state */	State		nextstate;		/* next run state */	uchar	*stk;			/* top of stack (lowest address of stack) */	uint		stksize;		/* stack size */	Thread	*next;		/* next on ready queue */ 	Proc		*proc;		/* proc of this thread */	Thread	*nextt;		/* next on list of threads in this proc*/	int		ret;			/* return value for Exec, Fork */ 	char		*cmdname;	/* ptr to name of thread */ 	int		inrendez;	Thread	*rendhash;	/* Trgrp linked list */	ulong	rendtag;		/* rendezvous tag */	ulong	rendval;		/* rendezvous value */	int		rendbreak;	/* rendezvous has been taken */ 	Chanstate	chan;		/* which channel operation is current */	Alt		*alt;			/* pointer to current alt structure (debugging) */ 	void*	udata;		/* User per-thread data pointer */}; struct Execargs{	char		*prog;	char		**args;	int		fd[2];}; struct Proc{	Lock		lock;	jmp_buf	sched;		/* for context switches */	int		pid;			/* process id */	int		splhi;		/* delay notes */	Thread	*thread;		/* running thread */ 	int		needexec;	Execargs	exec;		/* exec argument */	Proc		*newproc;	/* fork argument */	char		exitstr[ERRMAX];	/* exit status */ 	int		rforkflag;	int		nthreads;	Tqueue	threads;		/* All threads of this proc */	Tqueue	ready;		/* Runnable threads */	Lock		readylock; 	char		printbuf[Printsize];	int		blocked;		/* In a rendezvous */	int		pending;		/* delayed note pending */	int		nonotes;		/*  delay notes */	uint		nextID;		/* ID of most recently created thread */	Proc		*next;		/* linked list of Procs */ 	void		*arg;			/* passed between shared and unshared stk */	char		str[ERRMAX];	/* used by threadexits to avoid malloc */ 	void*	udata;		/* User per-proc data pointer */}; struct Pqueue {		/* Proc queue */	Lock		lock;	Proc		*head;	Proc		**tail;}; void		_freeproc(Proc*);void		_freethread(Thread*);Proc*	_newproc(void(*)(void*), void*, uint, char*, int, int);int		_procsplhi(void);void		_procsplx(int);void		_sched(void);int		_schedexec(Execargs*);void		_schedexecwait(void);void		_schedexit(Proc*);int		_schedfork(Proc*);void		_schedinit(void*);void		_systhreadinit(void);void		_threadassert(char*);void		_threadbreakrendez(void);void		_threaddebug(ulong, char*, ...);void		_threadexitsall(char*);void		_threadflagrendez(Thread*);Proc*	_threadgetproc(void);void		_threadsetproc(Proc*);void		_threadinitstack(Thread*, void(*)(void*), void*);void*	_threadmalloc(long, int);void		_threadnote(void*, char*);void		_threadready(Thread*);ulong	_threadrendezvous(ulong, ulong);void		_threadsignal(void);void		_threadsysfatal(char*, va_list);long		_xdec(long*);void		_xinc(long*); extern int			_threaddebuglevel;extern char*		_threadexitsallstatus;extern Pqueue		_threadpq;extern Channel*	_threadwaitchan;extern Rgrp		_threadrgrp; #define DBGAPPL	(1 << 0)#define DBGSCHED	(1 << 16)#define DBGCHAN	(1 << 17)#define DBGREND	(1 << 18)/* #define DBGKILL	(1 << 19) */#define DBGNOTE	(1 << 20)#define DBGEXEC	(1 << 21)