zfs/include/os/linux/spl/sys/condvar.h

/*
 *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
 *  Copyright (C) 2007 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
 *  UCRL-CODE-235197
 *
 *  This file is part of the SPL, Solaris Porting Layer.
 *
 *  The SPL is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  option) any later version.
 *
 *  The SPL is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _SPL_CONDVAR_H
#define	_SPL_CONDVAR_H

#include <linux/module.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/callo.h>
#include <sys/wait.h>
#include <sys/time.h>

/*
 * cv_timedwait() is similar to cv_wait() except that it additionally expects
 * a timeout value specified in ticks.  When woken by cv_signal() or
 * cv_broadcast() it returns 1, otherwise when the timeout is reached -1 is
 * returned.
 *
 * cv_timedwait_sig() behaves the same as cv_timedwait() but blocks
 * interruptibly and can be woken by a signal (EINTR, ERESTART).  When
 * this occurs 0 is returned.
 *
 * cv_timedwait_io() and cv_timedwait_sig_io() are variants of cv_timedwait()
 * and cv_timedwait_sig() which should be used when waiting for outstanding
 * IO to complete.  They are responsible for updating the iowait accounting
 * when this is supported by the platform.
 *
 * cv_timedwait_hires() and cv_timedwait_sig_hires() are high resolution
 * versions of cv_timedwait() and cv_timedwait_sig().  They expect the timeout
 * to be specified as a hrtime_t allowing for timeouts of less than a tick.
 *
 * N.B. The return values differ slightly from the illumos implementation
 * which returns the time remaining, instead of 1, when woken.  They both
 * return -1 on timeout. Consumers which need to know the time remaining
 * are responsible for tracking it themselves.
 */


/*
 * The kcondvar_t struct is protected by mutex taken externally before
 * calling any of the wait/signal funs, and passed into the wait funs.
 */
#define	CV_MAGIC			0x346545f4
#define	CV_DESTROY			0x346545f5

typedef struct {
	int cv_magic;
	spl_wait_queue_head_t cv_event;
	spl_wait_queue_head_t cv_destroy;
	atomic_t cv_refs;
	atomic_t cv_waiters;
	kmutex_t *cv_mutex;
} kcondvar_t;

typedef enum { CV_DEFAULT = 0, CV_DRIVER } kcv_type_t;

extern void __cv_init(kcondvar_t *, char *, kcv_type_t, void *);
extern void __cv_destroy(kcondvar_t *);
extern void __cv_wait(kcondvar_t *, kmutex_t *);
extern void __cv_wait_io(kcondvar_t *, kmutex_t *);
extern void __cv_wait_idle(kcondvar_t *, kmutex_t *);
extern int __cv_wait_io_sig(kcondvar_t *, kmutex_t *);
extern int __cv_wait_sig(kcondvar_t *, kmutex_t *);
extern int __cv_timedwait(kcondvar_t *, kmutex_t *, clock_t);
extern int __cv_timedwait_io(kcondvar_t *, kmutex_t *, clock_t);
extern int __cv_timedwait_sig(kcondvar_t *, kmutex_t *, clock_t);
extern int __cv_timedwait_idle(kcondvar_t *, kmutex_t *, clock_t);
extern int cv_timedwait_hires(kcondvar_t *, kmutex_t *, hrtime_t,
    hrtime_t res, int flag);
extern int cv_timedwait_sig_hires(kcondvar_t *, kmutex_t *, hrtime_t,
    hrtime_t res, int flag);
extern int cv_timedwait_idle_hires(kcondvar_t *, kmutex_t *, hrtime_t,
    hrtime_t res, int flag);
extern void __cv_signal(kcondvar_t *);
extern void __cv_broadcast(kcondvar_t *c);

#define	cv_init(cvp, name, type, arg)		__cv_init(cvp, name, type, arg)
#define	cv_destroy(cvp)				__cv_destroy(cvp)
#define	cv_wait(cvp, mp)			__cv_wait(cvp, mp)
#define	cv_wait_io(cvp, mp)			__cv_wait_io(cvp, mp)
#define	cv_wait_idle(cvp, mp)			__cv_wait_idle(cvp, mp)
#define	cv_wait_io_sig(cvp, mp)			__cv_wait_io_sig(cvp, mp)
#define	cv_wait_sig(cvp, mp)			__cv_wait_sig(cvp, mp)
#define	cv_signal(cvp)				__cv_signal(cvp)
#define	cv_broadcast(cvp)			__cv_broadcast(cvp)

/*
 * NB: There is no way to reliably distinguish between having been signalled
 * and having timed out on Linux. If the client code needs to reliably
 * distinguish between the two it should use the hires variant.
 */
#define	cv_timedwait(cvp, mp, t)		__cv_timedwait(cvp, mp, t)
#define	cv_timedwait_io(cvp, mp, t)		__cv_timedwait_io(cvp, mp, t)
#define	cv_timedwait_sig(cvp, mp, t)		__cv_timedwait_sig(cvp, mp, t)
#define	cv_timedwait_idle(cvp, mp, t)		__cv_timedwait_idle(cvp, mp, t)


#endif /* _SPL_CONDVAR_H */