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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2000 Silicon Graphics, Inc. All rights reserved
*
* This implemenation of synchronization variables is heavily based on
* one done by Steve Lord <lord@sgi.com>
*
* Paul Cassella <pwc@sgi.com>
*/
#ifndef SV_H
#define SV_H
#include <linux/spinlock.h>
#include <asm/semaphore.h>
#ifndef ASSERT
#define ASSERT(x) do { \
if(!(x)) { \
printk(KERN_ERR "%s\n", "Assertion failed: " # x); \
BUG(); \
} \
} while(0)
#define _SV_ASSERT
#endif
typedef void sv_mon_lock_t;
typedef void (*sv_mon_unlock_func_t)(sv_mon_lock_t *lock);
/* sv_flags values: */
#define SV_ORDER_FIFO 0x001
#define SV_ORDER_FILO 0x002
#define SV_ORDER_LIFO SV_ORDER_FILO
/* If at some point one order becomes preferable to others, we can
switch to it if the caller of sv_init doesn't specify. */
#define SV_ORDER_DEFAULT SV_ORDER_FIFO
#define SV_ORDER_MASK 0x00f
#define SV_MON_SEMA 0x010
#define SV_MON_SPIN 0x020
#define SV_MON_MASK 0x0f0
/*
If the monitor lock can be aquired from interrupts. Note that this
is a superset of the cases in which the sv can be touched from
interrupts.
This is currently only valid when the monitor lock is a spinlock.
If this is used, sv_wait, sv_signal, and sv_broadcast must all be
called with interrupts disabled, which has to happen anyway to have
acquired the monitor spinlock.
*/
#define SV_INTS 0x100
/* ditto for bottom halves */
#define SV_BHS 0x200
/* sv_wait_flag values: */
#define SV_WAIT_SIG 0x001 /* Allow sv_wait to be interrupted by a signal */
typedef struct sv_s {
wait_queue_head_t sv_waiters;
sv_mon_lock_t *sv_mon_lock; /* Lock held for exclusive access to monitor. */
sv_mon_unlock_func_t sv_mon_unlock_func;
spinlock_t sv_lock; /* Spinlock protecting the sv itself. */
int sv_flags;
} sv_t;
#define DECLARE_SYNC_VARIABLE(sv, l, f) sv_t sv = sv_init(&sv, l, f)
/*
* @sv the sync variable to initialize
* @monitor_lock the lock enforcing exclusive running in the monitor
* @flags one of
* SV_MON_SEMA monitor_lock is a semaphore
* SV_MON_SPIN monitor_lock is a spinlock
* and a bitwise or of some subset of
* SV_INTS - the monitor lock can be acquired from interrupts (and
* hence, whenever we hold it, interrupts are disabled or
* we're in an interrupt.) This is only valid when
* SV_MON_SPIN is set.
*/
void sv_init(sv_t *sv, sv_mon_lock_t *monitor_lock, int flags);
/*
* Set SV_WAIT_SIG in sv_wait_flags to let the sv_wait be interrupted by signals.
*
* timeout is how long to wait before giving up, or 0 to wait
* indefinately. It is given in jiffies, and is relative.
*
* The associated lock must be locked on entry. It is unlocked on return.
*
* Return values:
*
* n < 0 : interrupted, -n jiffies remaining on timeout, or -1 if timeout == 0
* n = 0 : timeout expired
* n > 0 : sv_signal()'d, n jiffies remaining on timeout, or 1 if timeout == 0
*/
extern signed long sv_wait(sv_t *sv, int sv_wait_flags,
unsigned long timeout /* relative jiffies */);
static inline int sv_wait_compat(sv_t *sv, sv_mon_lock_t *lock, int sv_wait_flags,
unsigned long timeout, int sv_mon_type)
{
ASSERT(sv_mon_type == (sv->sv_flags & SV_MON_MASK));
if(sv->sv_mon_lock)
ASSERT(lock == sv->sv_mon_lock);
else
sv->sv_mon_lock = lock;
return sv_wait(sv, sv_wait_flags, timeout);
}
/* These work like Irix's sv_wait() and sv_wait_sig(), except the
caller must call the one correpsonding to the type of the monitor
lock. */
#define sv_spin_wait(sv, lock) \
sv_wait_compat(sv, lock, 0, 0, SV_MON_SPIN)
#define sv_spin_wait_sig(sv, lock) \
sv_wait_compat(sv, lock, SV_WAIT_SIG, 0, SV_MON_SPIN)
#define sv_sema_wait(sv, lock) \
sv_wait_compat(sv, lock, 0, 0, SV_MON_SEMA)
#define sv_sema_wait_sig(sv, lock) \
sv_wait_compat(sv, lock, SV_WAIT_SIG, 0, SV_MON_SEMA)
/* These work as in Irix. */
void sv_signal(sv_t *sv);
void sv_broadcast(sv_t *sv);
/* This works as in Irix. */
void sv_destroy(sv_t *sv);
#ifdef _SV_ASSERT
#undef ASSERT
#undef _SV_ASSERT
#endif
#endif
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