freebsd-nq/sys/kern/kern_intr.c
John Baldwin de271f01c2 Work around a race condition where an interrupt handler can be removed from
an interrupt thread while the interrupt thread is blocked on Giant waiting
to execute the interrupt handler being removed.  The result was that the
intrhand structure would be free'd, and we would call 0xdeadc0de.  The work
around is to check to see if the interrupt thread is idle when removing a
handler.  If not, then we mark the interrupt handler as being dead using
the new IH_DEAD flag and don't remove it from the interrupt threads' list
of handlers.  When the interrupt thread resumes, it will see a dead handler
while traversing the list of handlers and will remove the handler then.
2001-02-22 02:18:32 +00:00

628 lines
16 KiB
C

/*
* Copyright (c) 1997, Stefan Esser <se@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*
*/
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/rtprio.h>
#include <sys/systm.h>
#include <sys/ipl.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/random.h>
#include <sys/resourcevar.h>
#include <sys/unistd.h>
#include <sys/vmmeter.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/stdarg.h>
#include <net/netisr.h> /* prototype for legacy_setsoftnet */
struct int_entropy {
struct proc *proc;
int vector;
};
void *net_ih;
void *vm_ih;
void *softclock_ih;
struct ithd *clk_ithd;
struct ithd *tty_ithd;
static struct mtx ithread_list_lock;
static MALLOC_DEFINE(M_ITHREAD, "ithread", "Interrupt Threads");
static void ithread_update(struct ithd *);
static void ithread_loop(void *);
static void ithread_init(void *);
static void start_softintr(void *);
static void swi_net(void *);
u_char
ithread_priority(enum intr_type flags)
{
u_char pri;
flags &= (INTR_TYPE_TTY | INTR_TYPE_BIO | INTR_TYPE_NET |
INTR_TYPE_CAM | INTR_TYPE_MISC | INTR_TYPE_CLK);
switch (flags) {
case INTR_TYPE_TTY:
pri = PI_TTYLOW;
break;
case INTR_TYPE_BIO:
/*
* XXX We need to refine this. BSD/OS distinguishes
* between tape and disk priorities.
*/
pri = PI_DISK;
break;
case INTR_TYPE_NET:
pri = PI_NET;
break;
case INTR_TYPE_CAM:
pri = PI_DISK; /* XXX or PI_CAM? */
break;
case INTR_TYPE_CLK:
pri = PI_REALTIME;
break;
case INTR_TYPE_MISC:
pri = PI_DULL; /* don't care */
break;
default:
/* We didn't specify an interrupt level. */
panic("ithread_priority: no interrupt type in flags");
}
return pri;
}
/*
* Regenerate the name (p_comm) and priority for a threaded interrupt thread.
*/
static void
ithread_update(struct ithd *ithd)
{
struct intrhand *ih;
struct proc *p;
int entropy;
p = ithd->it_proc;
if (p == NULL)
return;
strncpy(p->p_comm, ithd->it_name, sizeof(ithd->it_name));
ih = TAILQ_FIRST(&ithd->it_handlers);
if (ih == NULL) {
p->p_pri.pri_level = PRI_MAX_ITHD;
ithd->it_flags &= ~IT_ENTROPY;
return;
}
entropy = 0;
p->p_pri.pri_level = ih->ih_pri;
TAILQ_FOREACH(ih, &ithd->it_handlers, ih_next) {
if (strlen(p->p_comm) + strlen(ih->ih_name) + 1 <
sizeof(p->p_comm)) {
strcat(p->p_comm, " ");
strcat(p->p_comm, ih->ih_name);
} else if (strlen(p->p_comm) + 1 == sizeof(p->p_comm)) {
if (p->p_comm[sizeof(p->p_comm) - 2] == '+')
p->p_comm[sizeof(p->p_comm) - 2] = '*';
else
p->p_comm[sizeof(p->p_comm) - 2] = '+';
} else
strcat(p->p_comm, "+");
if (ih->ih_flags & IH_ENTROPY)
entropy++;
}
if (entropy)
ithd->it_flags |= IT_ENTROPY;
else
ithd->it_flags &= ~IT_ENTROPY;
CTR1(KTR_INTR, __func__ ": updated %s\n", p->p_comm);
}
int
ithread_create(struct ithd **ithread, int vector, int flags,
void (*disable)(int), void (*enable)(int), const char *fmt, ...)
{
struct ithd *ithd;
struct proc *p;
int error;
va_list ap;
/* The only valid flag during creation is IT_SOFT. */
if ((flags & ~IT_SOFT) != 0)
return (EINVAL);
ithd = malloc(sizeof(struct ithd), M_ITHREAD, M_WAITOK | M_ZERO);
ithd->it_vector = vector;
ithd->it_disable = disable;
ithd->it_enable = enable;
ithd->it_flags = flags;
TAILQ_INIT(&ithd->it_handlers);
va_start(ap, fmt);
vsnprintf(ithd->it_name, sizeof(ithd->it_name), fmt, ap);
va_end(ap);
error = kthread_create(ithread_loop, ithd, &p, RFSTOPPED | RFHIGHPID,
ithd->it_name);
if (error) {
free(ithd, M_ITHREAD);
return (error);
}
p->p_pri.pri_class = PRI_ITHD;
p->p_pri.pri_level = PRI_MAX_ITHD;
p->p_stat = SWAIT;
ithd->it_proc = p;
p->p_ithd = ithd;
if (ithread != NULL)
*ithread = ithd;
CTR1(KTR_INTR, __func__ ": created %s", ithd->it_name);
return (0);
}
int
ithread_destroy(struct ithd *ithread)
{
if (ithread == NULL || !TAILQ_EMPTY(&ithread->it_handlers))
return (EINVAL);
mtx_lock_spin(&sched_lock);
ithread->it_flags |= IT_DEAD;
if (ithread->it_proc->p_stat == SWAIT) {
ithread->it_proc->p_stat = SRUN;
setrunqueue(ithread->it_proc);
}
mtx_unlock_spin(&sched_lock);
CTR1(KTR_INTR, __func__ ": killing %s", ithread->it_name);
return (0);
}
int
ithread_add_handler(struct ithd* ithread, const char *name,
driver_intr_t handler, void *arg, u_char pri, enum intr_type flags,
void **cookiep)
{
struct intrhand *ih, *temp_ih;
if (ithread == NULL || name == NULL || handler == NULL)
return (EINVAL);
if ((flags & INTR_FAST) !=0)
flags |= INTR_EXCL;
ih = malloc(sizeof(struct intrhand), M_ITHREAD, M_WAITOK | M_ZERO);
ih->ih_handler = handler;
ih->ih_argument = arg;
ih->ih_name = name;
ih->ih_ithread = ithread;
ih->ih_pri = pri;
if (flags & INTR_FAST)
ih->ih_flags = IH_FAST | IH_EXCLUSIVE;
else if (flags & INTR_EXCL)
ih->ih_flags = IH_EXCLUSIVE;
if (flags & INTR_MPSAFE)
ih->ih_flags |= IH_MPSAFE;
if (flags & INTR_ENTROPY)
ih->ih_flags |= IH_ENTROPY;
mtx_lock_spin(&ithread_list_lock);
if ((flags & INTR_EXCL) !=0 && !TAILQ_EMPTY(&ithread->it_handlers))
goto fail;
if (!TAILQ_EMPTY(&ithread->it_handlers) &&
(TAILQ_FIRST(&ithread->it_handlers)->ih_flags & IH_EXCLUSIVE) != 0)
goto fail;
TAILQ_FOREACH(temp_ih, &ithread->it_handlers, ih_next)
if (temp_ih->ih_pri > ih->ih_pri)
break;
if (temp_ih == NULL)
TAILQ_INSERT_TAIL(&ithread->it_handlers, ih, ih_next);
else
TAILQ_INSERT_BEFORE(temp_ih, ih, ih_next);
ithread_update(ithread);
mtx_unlock_spin(&ithread_list_lock);
if (cookiep != NULL)
*cookiep = ih;
CTR2(KTR_INTR, __func__ ": added %s to %s", ih->ih_name,
ithread->it_name);
return (0);
fail:
mtx_unlock_spin(&ithread_list_lock);
free(ih, M_ITHREAD);
return (EINVAL);
}
int
ithread_remove_handler(void *cookie)
{
struct intrhand *handler = (struct intrhand *)cookie;
struct ithd *ithread;
#ifdef INVARIANTS
struct intrhand *ih;
#endif
if (handler == NULL)
return (EINVAL);
ithread = handler->ih_ithread;
KASSERT(ithread != NULL,
("interrupt handler \"%s\" has a NULL interrupt thread",
handler->ih_name));
CTR2(KTR_INTR, __func__ ": removing %s from %s", handler->ih_name,
ithread->it_name);
mtx_lock_spin(&ithread_list_lock);
#ifdef INVARIANTS
TAILQ_FOREACH(ih, &ithread->it_handlers, ih_next)
if (ih == handler)
goto ok;
mtx_unlock_spin(&ithread_list_lock);
panic("interrupt handler \"%s\" not found in interrupt thread \"%s\"",
ih->ih_name, ithread->it_name);
ok:
#endif
/*
* If the interrupt thread is already running, then just mark this
* handler as being dead and let the ithread do the actual removal.
*/
mtx_lock_spin(&sched_lock);
if (ithread->it_proc->p_stat != SWAIT) {
handler->ih_flags |= IH_DEAD;
/*
* Ensure that the thread will process the handler list
* again and remove this handler if it has already passed
* it on the list.
*/
ithread->it_need = 1;
} else {
TAILQ_REMOVE(&ithread->it_handlers, handler, ih_next);
ithread_update(ithread);
}
mtx_unlock_spin(&sched_lock);
mtx_unlock_spin(&ithread_list_lock);
if ((handler->ih_flags & IH_DEAD) == 0)
free(handler, M_ITHREAD);
return (0);
}
int
ithread_schedule(struct ithd *ithread, int do_switch)
{
struct int_entropy entropy;
struct proc *p;
intrmask_t saveintr;
/*
* If no ithread or no handlers, then we have a stray interrupt.
*/
if ((ithread == NULL) || TAILQ_EMPTY(&ithread->it_handlers))
return (EINVAL);
/*
* If any of the handlers for this ithread claim to be good
* sources of entropy, then gather some.
*/
if (harvest.interrupt && ithread->it_flags & IT_ENTROPY) {
entropy.vector = ithread->it_vector;
entropy.proc = CURPROC;
random_harvest(&entropy, sizeof(entropy), 2, 0,
RANDOM_INTERRUPT);
}
p = ithread->it_proc;
CTR3(KTR_INTR, __func__ ": pid %d: (%s) need = %d", p->p_pid, p->p_comm,
ithread->it_need);
/*
* Set it_need to tell the thread to keep running if it is already
* running. Then, grab sched_lock and see if we actually need to
* put this thread on the runqueue. If so and the do_switch flag is
* true, then switch to the ithread immediately. Otherwise, use
* need_resched() to guarantee that this ithread will run before any
* userland processes.
*/
ithread->it_need = 1;
mtx_lock_spin(&sched_lock);
if (p->p_stat == SWAIT) {
CTR1(KTR_INTR, __func__ ": setrunqueue %d", p->p_pid);
p->p_stat = SRUN;
setrunqueue(p);
if (do_switch) {
saveintr = sched_lock.mtx_saveintr;
mtx_intr_enable(&sched_lock);
if (curproc != PCPU_GET(idleproc))
setrunqueue(curproc);
curproc->p_stats->p_ru.ru_nvcsw++;
mi_switch();
sched_lock.mtx_saveintr = saveintr;
} else
need_resched();
} else {
CTR3(KTR_INTR, __func__ ": pid %d: it_need %d, state %d",
p->p_pid, ithread->it_need, p->p_stat);
}
mtx_unlock_spin(&sched_lock);
return (0);
}
int
swi_add(struct ithd **ithdp, const char *name, driver_intr_t handler,
void *arg, int pri, enum intr_type flags, void **cookiep)
{
struct ithd *ithd;
int error;
if (flags & (INTR_FAST | INTR_ENTROPY))
return (EINVAL);
ithd = (ithdp != NULL) ? *ithdp : NULL;
if (ithd != NULL) {
if ((ithd->it_flags & IT_SOFT) == 0)
return(EINVAL);
} else {
error = ithread_create(&ithd, pri, IT_SOFT, NULL, NULL,
"swi%d:", pri);
if (error)
return (error);
if (ithdp != NULL)
*ithdp = ithd;
}
return (ithread_add_handler(ithd, name, handler, arg,
(pri * RQ_PPQ) + PI_SOFT, flags, cookiep));
}
/*
* Schedule a heavyweight software interrupt process.
*/
void
swi_sched(void *cookie, int flags)
{
struct intrhand *ih = (struct intrhand *)cookie;
struct ithd *it = ih->ih_ithread;
int error;
atomic_add_int(&cnt.v_intr, 1); /* one more global interrupt */
CTR3(KTR_INTR, "swi_sched pid %d(%s) need=%d",
it->it_proc->p_pid, it->it_proc->p_comm, it->it_need);
/*
* Set ih_need for this handler so that if the ithread is already
* running it will execute this handler on the next pass. Otherwise,
* it will execute it the next time it runs.
*/
atomic_store_rel_int(&ih->ih_need, 1);
if (!(flags & SWI_DELAY)) {
error = ithread_schedule(it, !cold && flags & SWI_SWITCH);
KASSERT(error == 0, ("stray software interrupt"));
}
}
/*
* This is the main code for interrupt threads.
*/
void
ithread_loop(void *arg)
{
struct ithd *ithd; /* our thread context */
struct intrhand *ih; /* and our interrupt handler chain */
struct proc *p;
p = curproc;
ithd = (struct ithd *)arg; /* point to myself */
KASSERT(ithd->it_proc == p && p->p_ithd == ithd,
(__func__ ": ithread and proc linkage out of sync"));
/*
* As long as we have interrupts outstanding, go through the
* list of handlers, giving each one a go at it.
*/
for (;;) {
/*
* If we are an orphaned thread, then just die.
*/
if (ithd->it_flags & IT_DEAD) {
CTR2(KTR_INTR, __func__ ": pid %d: (%s) exiting",
p->p_pid, p->p_comm);
p->p_ithd = NULL;
mtx_lock(&Giant);
free(ithd, M_ITHREAD);
kthread_exit(0);
}
CTR3(KTR_INTR, __func__ ": pid %d: (%s) need=%d",
p->p_pid, p->p_comm, ithd->it_need);
while (ithd->it_need) {
/*
* Service interrupts. If another interrupt
* arrives while we are running, they will set
* it_need to denote that we should make
* another pass.
*/
atomic_store_rel_int(&ithd->it_need, 0);
restart:
TAILQ_FOREACH(ih, &ithd->it_handlers, ih_next) {
if (ithd->it_flags & IT_SOFT && !ih->ih_need)
continue;
atomic_store_rel_int(&ih->ih_need, 0);
CTR5(KTR_INTR,
__func__ ": pid %d ih=%p: %p(%p) flg=%x",
p->p_pid, (void *)ih,
(void *)ih->ih_handler, ih->ih_argument,
ih->ih_flags);
if ((ih->ih_flags & IH_MPSAFE) == 0)
mtx_lock(&Giant);
if ((ih->ih_flags & IH_DEAD) != 0) {
mtx_lock_spin(&ithread_list_lock);
TAILQ_REMOVE(&ithd->it_handlers, ih,
ih_next);
ithread_update(ithd);
mtx_unlock_spin(&ithread_list_lock);
if (!mtx_owned(&Giant))
mtx_lock(&Giant);
free(ih, M_ITHREAD);
mtx_unlock(&Giant);
goto restart;
}
ih->ih_handler(ih->ih_argument);
if ((ih->ih_flags & IH_MPSAFE) == 0)
mtx_unlock(&Giant);
}
}
/*
* Processed all our interrupts. Now get the sched
* lock. This may take a while and it_need may get
* set again, so we have to check it again.
*/
mtx_assert(&Giant, MA_NOTOWNED);
mtx_lock_spin(&sched_lock);
if (!ithd->it_need) {
/*
* Should we call this earlier in the loop above?
*/
if (ithd->it_enable != NULL)
ithd->it_enable(ithd->it_vector);
p->p_stat = SWAIT; /* we're idle */
CTR1(KTR_INTR, __func__ ": pid %d: done", p->p_pid);
mi_switch();
CTR1(KTR_INTR, __func__ ": pid %d: resumed", p->p_pid);
}
mtx_unlock_spin(&sched_lock);
}
}
/*
* Initialize mutex used to protect ithread handler lists.
*/
static void
ithread_init(void *dummy)
{
mtx_init(&ithread_list_lock, "ithread list lock", MTX_SPIN);
}
SYSINIT(ithread_init, SI_SUB_INTR, SI_ORDER_FIRST, ithread_init, NULL);
/*
* Start standard software interrupt threads
*/
static void
start_softintr(void *dummy)
{
if (swi_add(NULL, "net", swi_net, NULL, SWI_NET, 0, &net_ih) ||
swi_add(&clk_ithd, "clock", softclock, NULL, SWI_CLOCK,
INTR_MPSAFE, &softclock_ih) ||
swi_add(NULL, "vm", swi_vm, NULL, SWI_VM, 0, &vm_ih))
panic("died while creating standard software ithreads");
PROC_LOCK(clk_ithd->it_proc);
clk_ithd->it_proc->p_flag |= P_NOLOAD;
PROC_UNLOCK(clk_ithd->it_proc);
}
SYSINIT(start_softintr, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softintr, NULL)
void
legacy_setsoftnet(void)
{
swi_sched(net_ih, SWI_NOSWITCH);
}
/*
* XXX: This should really be in the network code somewhere and installed
* via a SI_SUB_SOFINTR, SI_ORDER_MIDDLE sysinit.
*/
void (*netisrs[32]) __P((void));
u_int netisr;
int
register_netisr(num, handler)
int num;
netisr_t *handler;
{
if (num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs)) ) {
printf("register_netisr: bad isr number: %d\n", num);
return (EINVAL);
}
netisrs[num] = handler;
return (0);
}
int
unregister_netisr(num)
int num;
{
if (num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs)) ) {
printf("unregister_netisr: bad isr number: %d\n", num);
return (EINVAL);
}
netisrs[num] = NULL;
return (0);
}
static void
swi_net(void *dummy)
{
u_int bits;
int i;
bits = atomic_readandclear_int(&netisr);
while ((i = ffs(bits)) != 0) {
i--;
if (netisrs[i] != NULL)
netisrs[i]();
else
printf("swi_net: unregistered isr number: %d.\n", i);
bits &= ~(1 << i);
}
}