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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/t_lock.h>
#include <sys/systm.h>
#include <sys/spl.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/kdi_impl.h>
/*
* Handle software interrupts through 'softcall' mechanism
*
* At present softcall mechanism uses a global list headed by softhead.
* Entries are added to tail and removed from head so as to preserve FIFO
* nature of entries in the softcall list. softcall() takes care of adding
* entries to the softtail.
*
* softint must take care of executing the entries in the FIFO
* order. It could be called simultaneously from multiple cpus, however only
* one instance of softint should process the softcall list, this is
* ensured by
* - the state the variable softcall_state will be at time to time.
* (IDLE->PEND->DRAIN->IDLE)
*
* These states are needed for softcall mechanism since Solaris has only
* one interface(ie. siron ) as of now for
* - raising a soft interrupt architecture independently(ie not through
* setsoftint(..) )
* - to process the softcall queue.
*/
#define NSOFTCALLS 200
/*
* Defined states for softcall processing.
*/
#define SOFT_IDLE 0x01 /* no processing is needed */
#define SOFT_PEND 0x02 /* softcall list needs processing */
#define SOFT_DRAIN 0x04 /* the list is being processed */
typedef struct softcall {
void (*sc_func)(void *); /* function to call */
void *sc_arg; /* arg to pass to func */
struct softcall *sc_next; /* next in list */
} softcall_t;
static softcall_t softcalls[NSOFTCALLS], *softhead, *softtail, *softfree;
static uint_t softcall_state;
/*
* protects softcall lists and control variable softcall_state.
*/
static kmutex_t softcall_lock;
static void (*kdi_softcall_func)(void);
extern void siron(void);
void
softcall_init(void)
{
softcall_t *sc;
for (sc = softcalls; sc < &softcalls[NSOFTCALLS]; sc++) {
sc->sc_next = softfree;
softfree = sc;
}
mutex_init(&softcall_lock, NULL, MUTEX_SPIN, (void *)ipltospl(SPL8));
}
/*
* Call function func with argument arg
* at some later time at software interrupt priority
*/
void
softcall(void (*func)(void *), void *arg)
{
softcall_t *sc;
/*
* protect against cross-calls
*/
mutex_enter(&softcall_lock);
/* coalesce identical softcalls */
for (sc = softhead; sc != 0; sc = sc->sc_next) {
if (sc->sc_func == func && sc->sc_arg == arg) {
mutex_exit(&softcall_lock);
return;
}
}
if ((sc = softfree) == 0)
panic("too many softcalls");
softfree = sc->sc_next;
sc->sc_func = func;
sc->sc_arg = arg;
sc->sc_next = 0;
if (softhead) {
softtail->sc_next = sc;
softtail = sc;
mutex_exit(&softcall_lock);
} else {
softhead = softtail = sc;
if (softcall_state == SOFT_DRAIN)
/*
* softint is already running; no need to
* raise a siron. Due to lock protection of
* softhead / softcall state, we know
* that softint() will see the new addition to
* the softhead queue.
*/
mutex_exit(&softcall_lock);
else {
softcall_state = SOFT_PEND;
mutex_exit(&softcall_lock);
siron();
}
}
}
void
kdi_softcall(void (*func)(void))
{
kdi_softcall_func = func;
if (softhead == NULL)
siron();
}
/*
* Called to process software interrupts take one off queue, call it,
* repeat.
*
* Note queue may change during call; softcall_lock and state variables
* softcall_state ensures that
* -we don't have multiple cpus pulling from the list (thus causing
* a violation of FIFO order).
* -we don't miss a new entry having been added to the head.
* -we don't miss a wakeup.
*/
void
softint(void)
{
softcall_t *sc;
void (*func)();
caddr_t arg;
/*
* Check if we are asked to process the softcall list.
*/
mutex_enter(&softcall_lock);
if (softcall_state != SOFT_PEND) {
mutex_exit(&softcall_lock);
goto out;
}
softcall_state = SOFT_DRAIN;
for (;;) {
if ((sc = softhead) != NULL) {
func = sc->sc_func;
arg = sc->sc_arg;
softhead = sc->sc_next;
sc->sc_next = softfree;
softfree = sc;
}
if (sc == NULL) {
softcall_state = SOFT_IDLE;
mutex_exit(&softcall_lock);
break;
}
mutex_exit(&softcall_lock);
func(arg);
mutex_enter(&softcall_lock);
}
out:
if ((func = kdi_softcall_func) != NULL) {
kdi_softcall_func = NULL;
func();
}
}
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