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kern_intr.c
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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 1997, Stefan Esser <[email protected]>
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include "opt_kstack_usage_prof.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/cpuset.h>
#include <sys/rtprio.h>
#include <sys/systm.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/epoch.h>
#include <sys/random.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/unistd.h>
#include <sys/vmmeter.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/smp.h>
#include <machine/stdarg.h>
#ifdef DDB
#include <ddb/ddb.h>
#include <ddb/db_sym.h>
#endif
/*
* Describe an interrupt thread. There is one of these per interrupt event.
*/
struct intr_thread {
struct intr_event *it_event;
struct thread *it_thread; /* Kernel thread. */
int it_flags; /* (j) IT_* flags. */
int it_need; /* Needs service. */
};
/* Interrupt thread flags kept in it_flags */
#define IT_DEAD 0x000001 /* Thread is waiting to exit. */
#define IT_WAIT 0x000002 /* Thread is waiting for completion. */
struct intr_entropy {
struct thread *td;
uintptr_t event;
};
struct intr_event *clk_intr_event;
struct intr_event *tty_intr_event;
void *vm_ih;
struct proc *intrproc;
static MALLOC_DEFINE(M_ITHREAD, "ithread", "Interrupt Threads");
static int intr_storm_threshold = 0;
SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold, CTLFLAG_RWTUN,
&intr_storm_threshold, 0,
"Number of consecutive interrupts before storm protection is enabled");
static int intr_epoch_batch = 1000;
SYSCTL_INT(_hw, OID_AUTO, intr_epoch_batch, CTLFLAG_RWTUN, &intr_epoch_batch,
0, "Maximum interrupt handler executions without re-entering epoch(9)");
static TAILQ_HEAD(, intr_event) event_list =
TAILQ_HEAD_INITIALIZER(event_list);
static struct mtx event_lock;
MTX_SYSINIT(intr_event_list, &event_lock, "intr event list", MTX_DEF);
static void intr_event_update(struct intr_event *ie);
static int intr_event_schedule_thread(struct intr_event *ie);
static struct intr_thread *ithread_create(const char *name);
static void ithread_destroy(struct intr_thread *ithread);
static void ithread_execute_handlers(struct proc *p,
struct intr_event *ie);
static void ithread_loop(void *);
static void ithread_update(struct intr_thread *ithd);
static void start_softintr(void *);
/* Map an interrupt type to an ithread priority. */
u_char
intr_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 | INTR_TYPE_AV);
switch (flags) {
case INTR_TYPE_TTY:
pri = PI_TTY;
break;
case INTR_TYPE_BIO:
pri = PI_DISK;
break;
case INTR_TYPE_NET:
pri = PI_NET;
break;
case INTR_TYPE_CAM:
pri = PI_DISK;
break;
case INTR_TYPE_AV:
pri = PI_AV;
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("intr_priority: no interrupt type in flags");
}
return pri;
}
/*
* Update an ithread based on the associated intr_event.
*/
static void
ithread_update(struct intr_thread *ithd)
{
struct intr_event *ie;
struct thread *td;
u_char pri;
ie = ithd->it_event;
td = ithd->it_thread;
mtx_assert(&ie->ie_lock, MA_OWNED);
/* Determine the overall priority of this event. */
if (CK_SLIST_EMPTY(&ie->ie_handlers))
pri = PRI_MAX_ITHD;
else
pri = CK_SLIST_FIRST(&ie->ie_handlers)->ih_pri;
/* Update name and priority. */
strlcpy(td->td_name, ie->ie_fullname, sizeof(td->td_name));
#ifdef KTR
sched_clear_tdname(td);
#endif
thread_lock(td);
sched_prio(td, pri);
thread_unlock(td);
}
/*
* Regenerate the full name of an interrupt event and update its priority.
*/
static void
intr_event_update(struct intr_event *ie)
{
struct intr_handler *ih;
char *last;
int missed, space, flags;
/* Start off with no entropy and just the name of the event. */
mtx_assert(&ie->ie_lock, MA_OWNED);
strlcpy(ie->ie_fullname, ie->ie_name, sizeof(ie->ie_fullname));
flags = 0;
missed = 0;
space = 1;
/* Run through all the handlers updating values. */
CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) {
if (strlen(ie->ie_fullname) + strlen(ih->ih_name) + 1 <
sizeof(ie->ie_fullname)) {
strcat(ie->ie_fullname, " ");
strcat(ie->ie_fullname, ih->ih_name);
space = 0;
} else
missed++;
flags |= ih->ih_flags;
}
ie->ie_hflags = flags;
/*
* If there is only one handler and its name is too long, just copy in
* as much of the end of the name (includes the unit number) as will
* fit. Otherwise, we have multiple handlers and not all of the names
* will fit. Add +'s to indicate missing names. If we run out of room
* and still have +'s to add, change the last character from a + to a *.
*/
if (missed == 1 && space == 1) {
ih = CK_SLIST_FIRST(&ie->ie_handlers);
missed = strlen(ie->ie_fullname) + strlen(ih->ih_name) + 2 -
sizeof(ie->ie_fullname);
strcat(ie->ie_fullname, (missed == 0) ? " " : "-");
strcat(ie->ie_fullname, &ih->ih_name[missed]);
missed = 0;
}
last = &ie->ie_fullname[sizeof(ie->ie_fullname) - 2];
while (missed-- > 0) {
if (strlen(ie->ie_fullname) + 1 == sizeof(ie->ie_fullname)) {
if (*last == '+') {
*last = '*';
break;
} else
*last = '+';
} else if (space) {
strcat(ie->ie_fullname, " +");
space = 0;
} else
strcat(ie->ie_fullname, "+");
}
/*
* If this event has an ithread, update it's priority and
* name.
*/
if (ie->ie_thread != NULL)
ithread_update(ie->ie_thread);
CTR2(KTR_INTR, "%s: updated %s", __func__, ie->ie_fullname);
}
int
intr_event_create(struct intr_event **event, void *source, int flags, int irq,
void (*pre_ithread)(void *), void (*post_ithread)(void *),
void (*post_filter)(void *), int (*assign_cpu)(void *, int),
const char *fmt, ...)
{
struct intr_event *ie;
va_list ap;
/* The only valid flag during creation is IE_SOFT. */
if ((flags & ~IE_SOFT) != 0)
return (EINVAL);
ie = malloc(sizeof(struct intr_event), M_ITHREAD, M_WAITOK | M_ZERO);
ie->ie_source = source;
ie->ie_pre_ithread = pre_ithread;
ie->ie_post_ithread = post_ithread;
ie->ie_post_filter = post_filter;
ie->ie_assign_cpu = assign_cpu;
ie->ie_flags = flags;
ie->ie_irq = irq;
ie->ie_cpu = NOCPU;
CK_SLIST_INIT(&ie->ie_handlers);
mtx_init(&ie->ie_lock, "intr event", NULL, MTX_DEF);
va_start(ap, fmt);
vsnprintf(ie->ie_name, sizeof(ie->ie_name), fmt, ap);
va_end(ap);
strlcpy(ie->ie_fullname, ie->ie_name, sizeof(ie->ie_fullname));
mtx_lock(&event_lock);
TAILQ_INSERT_TAIL(&event_list, ie, ie_list);
mtx_unlock(&event_lock);
if (event != NULL)
*event = ie;
CTR2(KTR_INTR, "%s: created %s", __func__, ie->ie_name);
return (0);
}
/*
* Bind an interrupt event to the specified CPU. Note that not all
* platforms support binding an interrupt to a CPU. For those
* platforms this request will fail. Using a cpu id of NOCPU unbinds
* the interrupt event.
*/
static int
_intr_event_bind(struct intr_event *ie, int cpu, bool bindirq, bool bindithread)
{
lwpid_t id;
int error;
/* Need a CPU to bind to. */
if (cpu != NOCPU && CPU_ABSENT(cpu))
return (EINVAL);
if (ie->ie_assign_cpu == NULL)
return (EOPNOTSUPP);
error = priv_check(curthread, PRIV_SCHED_CPUSET_INTR);
if (error)
return (error);
/*
* If we have any ithreads try to set their mask first to verify
* permissions, etc.
*/
if (bindithread) {
mtx_lock(&ie->ie_lock);
if (ie->ie_thread != NULL) {
id = ie->ie_thread->it_thread->td_tid;
mtx_unlock(&ie->ie_lock);
error = cpuset_setithread(id, cpu);
if (error)
return (error);
} else
mtx_unlock(&ie->ie_lock);
}
if (bindirq)
error = ie->ie_assign_cpu(ie->ie_source, cpu);
if (error) {
if (bindithread) {
mtx_lock(&ie->ie_lock);
if (ie->ie_thread != NULL) {
cpu = ie->ie_cpu;
id = ie->ie_thread->it_thread->td_tid;
mtx_unlock(&ie->ie_lock);
(void)cpuset_setithread(id, cpu);
} else
mtx_unlock(&ie->ie_lock);
}
return (error);
}
if (bindirq) {
mtx_lock(&ie->ie_lock);
ie->ie_cpu = cpu;
mtx_unlock(&ie->ie_lock);
}
return (error);
}
/*
* Bind an interrupt event to the specified CPU. For supported platforms, any
* associated ithreads as well as the primary interrupt context will be bound
* to the specificed CPU.
*/
int
intr_event_bind(struct intr_event *ie, int cpu)
{
return (_intr_event_bind(ie, cpu, true, true));
}
/*
* Bind an interrupt event to the specified CPU, but do not bind associated
* ithreads.
*/
int
intr_event_bind_irqonly(struct intr_event *ie, int cpu)
{
return (_intr_event_bind(ie, cpu, true, false));
}
/*
* Bind an interrupt event's ithread to the specified CPU.
*/
int
intr_event_bind_ithread(struct intr_event *ie, int cpu)
{
return (_intr_event_bind(ie, cpu, false, true));
}
/*
* Bind an interrupt event's ithread to the specified cpuset.
*/
int
intr_event_bind_ithread_cpuset(struct intr_event *ie, cpuset_t *cs)
{
lwpid_t id;
mtx_lock(&ie->ie_lock);
if (ie->ie_thread != NULL) {
id = ie->ie_thread->it_thread->td_tid;
mtx_unlock(&ie->ie_lock);
return (cpuset_setthread(id, cs));
} else {
mtx_unlock(&ie->ie_lock);
}
return (ENODEV);
}
static struct intr_event *
intr_lookup(int irq)
{
struct intr_event *ie;
mtx_lock(&event_lock);
TAILQ_FOREACH(ie, &event_list, ie_list)
if (ie->ie_irq == irq &&
(ie->ie_flags & IE_SOFT) == 0 &&
CK_SLIST_FIRST(&ie->ie_handlers) != NULL)
break;
mtx_unlock(&event_lock);
return (ie);
}
int
intr_setaffinity(int irq, int mode, void *m)
{
struct intr_event *ie;
cpuset_t *mask;
int cpu, n;
mask = m;
cpu = NOCPU;
/*
* If we're setting all cpus we can unbind. Otherwise make sure
* only one cpu is in the set.
*/
if (CPU_CMP(cpuset_root, mask)) {
for (n = 0; n < CPU_SETSIZE; n++) {
if (!CPU_ISSET(n, mask))
continue;
if (cpu != NOCPU)
return (EINVAL);
cpu = n;
}
}
ie = intr_lookup(irq);
if (ie == NULL)
return (ESRCH);
switch (mode) {
case CPU_WHICH_IRQ:
return (intr_event_bind(ie, cpu));
case CPU_WHICH_INTRHANDLER:
return (intr_event_bind_irqonly(ie, cpu));
case CPU_WHICH_ITHREAD:
return (intr_event_bind_ithread(ie, cpu));
default:
return (EINVAL);
}
}
int
intr_getaffinity(int irq, int mode, void *m)
{
struct intr_event *ie;
struct thread *td;
struct proc *p;
cpuset_t *mask;
lwpid_t id;
int error;
mask = m;
ie = intr_lookup(irq);
if (ie == NULL)
return (ESRCH);
error = 0;
CPU_ZERO(mask);
switch (mode) {
case CPU_WHICH_IRQ:
case CPU_WHICH_INTRHANDLER:
mtx_lock(&ie->ie_lock);
if (ie->ie_cpu == NOCPU)
CPU_COPY(cpuset_root, mask);
else
CPU_SET(ie->ie_cpu, mask);
mtx_unlock(&ie->ie_lock);
break;
case CPU_WHICH_ITHREAD:
mtx_lock(&ie->ie_lock);
if (ie->ie_thread == NULL) {
mtx_unlock(&ie->ie_lock);
CPU_COPY(cpuset_root, mask);
} else {
id = ie->ie_thread->it_thread->td_tid;
mtx_unlock(&ie->ie_lock);
error = cpuset_which(CPU_WHICH_TID, id, &p, &td, NULL);
if (error != 0)
return (error);
CPU_COPY(&td->td_cpuset->cs_mask, mask);
PROC_UNLOCK(p);
}
default:
return (EINVAL);
}
return (0);
}
int
intr_event_destroy(struct intr_event *ie)
{
mtx_lock(&event_lock);
mtx_lock(&ie->ie_lock);
if (!CK_SLIST_EMPTY(&ie->ie_handlers)) {
mtx_unlock(&ie->ie_lock);
mtx_unlock(&event_lock);
return (EBUSY);
}
TAILQ_REMOVE(&event_list, ie, ie_list);
#ifndef notyet
if (ie->ie_thread != NULL) {
ithread_destroy(ie->ie_thread);
ie->ie_thread = NULL;
}
#endif
mtx_unlock(&ie->ie_lock);
mtx_unlock(&event_lock);
mtx_destroy(&ie->ie_lock);
free(ie, M_ITHREAD);
return (0);
}
static struct intr_thread *
ithread_create(const char *name)
{
struct intr_thread *ithd;
struct thread *td;
int error;
ithd = malloc(sizeof(struct intr_thread), M_ITHREAD, M_WAITOK | M_ZERO);
error = kproc_kthread_add(ithread_loop, ithd, &intrproc,
&td, RFSTOPPED | RFHIGHPID,
0, "intr", "%s", name);
if (error)
panic("kproc_create() failed with %d", error);
thread_lock(td);
sched_class(td, PRI_ITHD);
TD_SET_IWAIT(td);
thread_unlock(td);
td->td_pflags |= TDP_ITHREAD;
ithd->it_thread = td;
CTR2(KTR_INTR, "%s: created %s", __func__, name);
return (ithd);
}
static void
ithread_destroy(struct intr_thread *ithread)
{
struct thread *td;
CTR2(KTR_INTR, "%s: killing %s", __func__, ithread->it_event->ie_name);
td = ithread->it_thread;
thread_lock(td);
ithread->it_flags |= IT_DEAD;
if (TD_AWAITING_INTR(td)) {
TD_CLR_IWAIT(td);
sched_add(td, SRQ_INTR);
} else
thread_unlock(td);
}
int
intr_event_add_handler(struct intr_event *ie, const char *name,
driver_filter_t filter, driver_intr_t handler, void *arg, u_char pri,
enum intr_type flags, void **cookiep)
{
struct intr_handler *ih, *temp_ih;
struct intr_handler **prevptr;
struct intr_thread *it;
if (ie == NULL || name == NULL || (handler == NULL && filter == NULL))
return (EINVAL);
/* Allocate and populate an interrupt handler structure. */
ih = malloc(sizeof(struct intr_handler), M_ITHREAD, M_WAITOK | M_ZERO);
ih->ih_filter = filter;
ih->ih_handler = handler;
ih->ih_argument = arg;
strlcpy(ih->ih_name, name, sizeof(ih->ih_name));
ih->ih_event = ie;
ih->ih_pri = pri;
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;
if (flags & INTR_TYPE_NET)
ih->ih_flags |= IH_NET;
/* We can only have one exclusive handler in a event. */
mtx_lock(&ie->ie_lock);
if (!CK_SLIST_EMPTY(&ie->ie_handlers)) {
if ((flags & INTR_EXCL) ||
(CK_SLIST_FIRST(&ie->ie_handlers)->ih_flags & IH_EXCLUSIVE)) {
mtx_unlock(&ie->ie_lock);
free(ih, M_ITHREAD);
return (EINVAL);
}
}
/* Create a thread if we need one. */
while (ie->ie_thread == NULL && handler != NULL) {
if (ie->ie_flags & IE_ADDING_THREAD)
msleep(ie, &ie->ie_lock, 0, "ithread", 0);
else {
ie->ie_flags |= IE_ADDING_THREAD;
mtx_unlock(&ie->ie_lock);
it = ithread_create("intr: newborn");
mtx_lock(&ie->ie_lock);
ie->ie_flags &= ~IE_ADDING_THREAD;
ie->ie_thread = it;
it->it_event = ie;
ithread_update(it);
wakeup(ie);
}
}
/* Add the new handler to the event in priority order. */
CK_SLIST_FOREACH_PREVPTR(temp_ih, prevptr, &ie->ie_handlers, ih_next) {
if (temp_ih->ih_pri > ih->ih_pri)
break;
}
CK_SLIST_INSERT_PREVPTR(prevptr, temp_ih, ih, ih_next);
intr_event_update(ie);
CTR3(KTR_INTR, "%s: added %s to %s", __func__, ih->ih_name,
ie->ie_name);
mtx_unlock(&ie->ie_lock);
if (cookiep != NULL)
*cookiep = ih;
return (0);
}
/*
* Append a description preceded by a ':' to the name of the specified
* interrupt handler.
*/
int
intr_event_describe_handler(struct intr_event *ie, void *cookie,
const char *descr)
{
struct intr_handler *ih;
size_t space;
char *start;
mtx_lock(&ie->ie_lock);
#ifdef INVARIANTS
CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) {
if (ih == cookie)
break;
}
if (ih == NULL) {
mtx_unlock(&ie->ie_lock);
panic("handler %p not found in interrupt event %p", cookie, ie);
}
#endif
ih = cookie;
/*
* Look for an existing description by checking for an
* existing ":". This assumes device names do not include
* colons. If one is found, prepare to insert the new
* description at that point. If one is not found, find the
* end of the name to use as the insertion point.
*/
start = strchr(ih->ih_name, ':');
if (start == NULL)
start = strchr(ih->ih_name, 0);
/*
* See if there is enough remaining room in the string for the
* description + ":". The "- 1" leaves room for the trailing
* '\0'. The "+ 1" accounts for the colon.
*/
space = sizeof(ih->ih_name) - (start - ih->ih_name) - 1;
if (strlen(descr) + 1 > space) {
mtx_unlock(&ie->ie_lock);
return (ENOSPC);
}
/* Append a colon followed by the description. */
*start = ':';
strcpy(start + 1, descr);
intr_event_update(ie);
mtx_unlock(&ie->ie_lock);
return (0);
}
/*
* Return the ie_source field from the intr_event an intr_handler is
* associated with.
*/
void *
intr_handler_source(void *cookie)
{
struct intr_handler *ih;
struct intr_event *ie;
ih = (struct intr_handler *)cookie;
if (ih == NULL)
return (NULL);
ie = ih->ih_event;
KASSERT(ie != NULL,
("interrupt handler \"%s\" has a NULL interrupt event",
ih->ih_name));
return (ie->ie_source);
}
/*
* If intr_event_handle() is running in the ISR context at the time of the call,
* then wait for it to complete.
*/
static void
intr_event_barrier(struct intr_event *ie)
{
int phase;
mtx_assert(&ie->ie_lock, MA_OWNED);
phase = ie->ie_phase;
/*
* Switch phase to direct future interrupts to the other active counter.
* Make sure that any preceding stores are visible before the switch.
*/
KASSERT(ie->ie_active[!phase] == 0, ("idle phase has activity"));
atomic_store_rel_int(&ie->ie_phase, !phase);
/*
* This code cooperates with wait-free iteration of ie_handlers
* in intr_event_handle.
* Make sure that the removal and the phase update are not reordered
* with the active count check.
* Note that no combination of acquire and release fences can provide
* that guarantee as Store->Load sequences can always be reordered.
*/
atomic_thread_fence_seq_cst();
/*
* Now wait on the inactive phase.
* The acquire fence is needed so that that all post-barrier accesses
* are after the check.
*/
while (ie->ie_active[phase] > 0)
cpu_spinwait();
atomic_thread_fence_acq();
}
static void
intr_handler_barrier(struct intr_handler *handler)
{
struct intr_event *ie;
ie = handler->ih_event;
mtx_assert(&ie->ie_lock, MA_OWNED);
KASSERT((handler->ih_flags & IH_DEAD) == 0,
("update for a removed handler"));
if (ie->ie_thread == NULL) {
intr_event_barrier(ie);
return;
}
if ((handler->ih_flags & IH_CHANGED) == 0) {
handler->ih_flags |= IH_CHANGED;
intr_event_schedule_thread(ie);
}
while ((handler->ih_flags & IH_CHANGED) != 0)
msleep(handler, &ie->ie_lock, 0, "ih_barr", 0);
}
/*
* Sleep until an ithread finishes executing an interrupt handler.
*
* XXX Doesn't currently handle interrupt filters or fast interrupt
* handlers. This is intended for LinuxKPI drivers only.
* Do not use in BSD code.
*/
void
_intr_drain(int irq)
{
struct intr_event *ie;
struct intr_thread *ithd;
struct thread *td;
ie = intr_lookup(irq);
if (ie == NULL)
return;
if (ie->ie_thread == NULL)
return;
ithd = ie->ie_thread;
td = ithd->it_thread;
/*
* We set the flag and wait for it to be cleared to avoid
* long delays with potentially busy interrupt handlers
* were we to only sample TD_AWAITING_INTR() every tick.
*/
thread_lock(td);
if (!TD_AWAITING_INTR(td)) {
ithd->it_flags |= IT_WAIT;
while (ithd->it_flags & IT_WAIT) {
thread_unlock(td);
pause("idrain", 1);
thread_lock(td);
}
}
thread_unlock(td);
return;
}
int
intr_event_remove_handler(void *cookie)
{
struct intr_handler *handler = (struct intr_handler *)cookie;
struct intr_event *ie;
struct intr_handler *ih;
struct intr_handler **prevptr;
#ifdef notyet
int dead;
#endif
if (handler == NULL)
return (EINVAL);
ie = handler->ih_event;
KASSERT(ie != NULL,
("interrupt handler \"%s\" has a NULL interrupt event",
handler->ih_name));
mtx_lock(&ie->ie_lock);
CTR3(KTR_INTR, "%s: removing %s from %s", __func__, handler->ih_name,
ie->ie_name);
CK_SLIST_FOREACH_PREVPTR(ih, prevptr, &ie->ie_handlers, ih_next) {
if (ih == handler)
break;
}
if (ih == NULL) {
panic("interrupt handler \"%s\" not found in "
"interrupt event \"%s\"", handler->ih_name, ie->ie_name);
}
/*
* If there is no ithread, then directly remove the handler. Note that
* intr_event_handle() iterates ie_handlers in a lock-less fashion, so
* care needs to be taken to keep ie_handlers consistent and to free
* the removed handler only when ie_handlers is quiescent.
*/
if (ie->ie_thread == NULL) {
CK_SLIST_REMOVE_PREVPTR(prevptr, ih, ih_next);
intr_event_barrier(ie);
intr_event_update(ie);
mtx_unlock(&ie->ie_lock);
free(handler, M_ITHREAD);
return (0);
}
/*
* Let the interrupt thread do the job.
* The interrupt source is disabled when the interrupt thread is
* running, so it does not have to worry about interaction with
* intr_event_handle().
*/
KASSERT((handler->ih_flags & IH_DEAD) == 0,
("duplicate handle remove"));
handler->ih_flags |= IH_DEAD;
intr_event_schedule_thread(ie);
while (handler->ih_flags & IH_DEAD)
msleep(handler, &ie->ie_lock, 0, "iev_rmh", 0);
intr_event_update(ie);
#ifdef notyet
/*
* XXX: This could be bad in the case of ppbus(8). Also, I think
* this could lead to races of stale data when servicing an
* interrupt.
*/
dead = 1;
CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) {
if (ih->ih_handler != NULL) {
dead = 0;
break;
}
}
if (dead) {
ithread_destroy(ie->ie_thread);
ie->ie_thread = NULL;
}
#endif
mtx_unlock(&ie->ie_lock);
free(handler, M_ITHREAD);
return (0);
}
int
intr_event_suspend_handler(void *cookie)
{
struct intr_handler *handler = (struct intr_handler *)cookie;
struct intr_event *ie;
if (handler == NULL)
return (EINVAL);
ie = handler->ih_event;
KASSERT(ie != NULL,
("interrupt handler \"%s\" has a NULL interrupt event",
handler->ih_name));
mtx_lock(&ie->ie_lock);
handler->ih_flags |= IH_SUSP;
intr_handler_barrier(handler);
mtx_unlock(&ie->ie_lock);
return (0);
}
int
intr_event_resume_handler(void *cookie)
{
struct intr_handler *handler = (struct intr_handler *)cookie;
struct intr_event *ie;
if (handler == NULL)
return (EINVAL);
ie = handler->ih_event;
KASSERT(ie != NULL,
("interrupt handler \"%s\" has a NULL interrupt event",
handler->ih_name));
/*
* intr_handler_barrier() acts not only as a barrier,
* it also allows to check for any pending interrupts.
*/
mtx_lock(&ie->ie_lock);
handler->ih_flags &= ~IH_SUSP;
intr_handler_barrier(handler);
mtx_unlock(&ie->ie_lock);
return (0);
}
static int
intr_event_schedule_thread(struct intr_event *ie)
{
struct intr_entropy entropy;
struct intr_thread *it;
struct thread *td;
struct thread *ctd;
/*
* If no ithread or no handlers, then we have a stray interrupt.
*/
if (ie == NULL || CK_SLIST_EMPTY(&ie->ie_handlers) ||
ie->ie_thread == NULL)
return (EINVAL);
ctd = curthread;
it = ie->ie_thread;
td = it->it_thread;
/*
* If any of the handlers for this ithread claim to be good
* sources of entropy, then gather some.
*/
if (ie->ie_hflags & IH_ENTROPY) {
entropy.event = (uintptr_t)ie;
entropy.td = ctd;
random_harvest_queue(&entropy, sizeof(entropy), RANDOM_INTERRUPT);
}
KASSERT(td->td_proc != NULL, ("ithread %s has no process", ie->ie_name));
/*
* Set it_need to tell the thread to keep running if it is already
* running. Then, lock the thread and see if we actually need to
* put it on the runqueue.
*
* Use store_rel to arrange that the store to ih_need in
* swi_sched() is before the store to it_need and prepare for
* transfer of this order to loads in the ithread.
*/
atomic_store_rel_int(&it->it_need, 1);
thread_lock(td);
if (TD_AWAITING_INTR(td)) {
CTR3(KTR_INTR, "%s: schedule pid %d (%s)", __func__, td->td_proc->p_pid,
td->td_name);
TD_CLR_IWAIT(td);
sched_add(td, SRQ_INTR);
} else {
CTR5(KTR_INTR, "%s: pid %d (%s): it_need %d, state %d",
__func__, td->td_proc->p_pid, td->td_name, it->it_need, td->td_state);
thread_unlock(td);
}
return (0);
}