mirror_zfs/include/sys/condvar.h
Neependra Khare 3f688a8c38 Add cv_timedwait_interruptible() function
The cv_timedwait() function by definition must wait unconditionally
for cv_signal()/cv_broadcast() before waking.  This causes processes
to go in the D state which increases the load average.  The load
average is the summation of processes in D state and run queue.

To avoid this it can be desirable to sleep interruptibly.  These
processes do not count against the load average but may be woken by
a signal.  It is up to the caller to determine why the process
was woken it may be for one of three reasons.

  1) cv_signal()/cv_broadcast()
  2) the timeout expired
  3) a signal was received

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2011-01-11 12:14:48 -08:00

78 lines
3.1 KiB
C

/*****************************************************************************\
* 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.
* For details, see <http://github.com/behlendorf/spl/>.
*
* 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 <linux/wait.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
/*
* 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_POISON 0x95
typedef struct {
int cv_magic;
char *cv_name;
int cv_name_size;
wait_queue_head_t cv_event;
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 *cvp, char *name, kcv_type_t type, void *arg);
extern void __cv_destroy(kcondvar_t *cvp);
extern void __cv_wait(kcondvar_t *cvp, kmutex_t *mp);
extern void __cv_wait_interruptible(kcondvar_t *cvp, kmutex_t *mp);
extern clock_t __cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time);
extern clock_t __cv_timedwait_interruptible(kcondvar_t *cvp, kmutex_t *mp,
clock_t exp_time);
extern void __cv_signal(kcondvar_t *cvp);
extern void __cv_broadcast(kcondvar_t *cvp);
#define cv_init(cvp, name, type, arg) \
({ \
if ((name) == NULL) \
__cv_init(cvp, #cvp, type, arg); \
else \
__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_interruptible(cvp, mp) __cv_wait_interruptible(cvp,mp)
#define cv_timedwait(cvp, mp, t) __cv_timedwait(cvp, mp, t)
#define cv_timedwait_interruptible(cvp, mp, t) \
__cv_timedwait_interruptible(cvp, mp, t)
#define cv_signal(cvp) __cv_signal(cvp)
#define cv_broadcast(cvp) __cv_broadcast(cvp)
#endif /* _SPL_CONDVAR_H */