freebsd-dev/sys/kern/kern_intr.c
Andriy Gapon 82a5a27527 add support for marking interrupt handlers as suspended
The goal of this change is to fix a problem with PCI shared interrupts
during suspend and resume.

I have observed a couple of variations of the following scenario.
Devices A and B are on the same PCI bus and share the same interrupt.
Device A's driver is suspended first and the device is powered down.
Device B generates an interrupt. Interrupt handlers of both drivers are
called. Device A's interrupt handler accesses registers of the powered
down device and gets back bogus values (I assume all 0xff). That data is
interpreted as interrupt status bits, etc. So, the interrupt handler
gets confused and may produce some noise or enter an infinite loop, etc.

This change affects only PCI devices.  The pci(4) bus driver marks a
child's interrupt handler as suspended after the child's suspend method
is called and before the device is powered down.  This is done only for
traditional PCI interrupts, because only they can be shared.

At the moment the change is only for x86.

Notable changes in core subsystems / interfaces:
- BUS_SUSPEND_INTR and BUS_RESUME_INTR methods are added to bus
  interface along with convenience functions bus_suspend_intr and
  bus_resume_intr;
- rman_set_irq_cookie and rman_get_irq_cookie functions are added to
  provide a way to associate an interrupt resource with an interrupt
  cookie;
- intr_event_suspend_handler and intr_event_resume_handler functions
  are added to the MI interrupt handler interface.

I added two new interrupt handler flags, IH_SUSP and IH_CHANGED, to
implement the new intr_event functions.  IH_SUSP marks a suspended
interrupt handler.  IH_CHANGED is used to implement a barrier that
ensures that a change to the interrupt handler's state is visible
to future interrupts.
While there, I fixed some whitespace issues in comments and changed a
couple of logically boolean variables to be bool.

MFC after:	1 month (maybe)
Differential Revision: https://reviews.freebsd.org/D15755
2018-12-17 17:11:00 +00:00

1600 lines
38 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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.
*/
#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/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/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 = 1000;
SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold, CTLFLAG_RWTUN,
&intr_storm_threshold, 0,
"Number of consecutive interrupts before storm protection is enabled");
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;
/* 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));
ie->ie_flags &= ~IE_ENTROPY;
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++;
if (ih->ih_flags & IH_ENTROPY)
ie->ie_flags |= IE_ENTROPY;
}
/*
* If the handler names were too long, 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 *.
*/
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));
}
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);
}
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;
/* 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 compatibility with linux 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_flags & IE_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);
}
/*
* Allow interrupt event binding for software interrupt handlers -- a no-op,
* since interrupts are generated in software rather than being directed by
* a PIC.
*/
static int
swi_assign_cpu(void *arg, int cpu)
{
return (0);
}
/*
* Add a software interrupt handler to a specified event. If a given event
* is not specified, then a new event is created.
*/
int
swi_add(struct intr_event **eventp, const char *name, driver_intr_t handler,
void *arg, int pri, enum intr_type flags, void **cookiep)
{
struct intr_event *ie;
int error;
if (flags & INTR_ENTROPY)
return (EINVAL);
ie = (eventp != NULL) ? *eventp : NULL;
if (ie != NULL) {
if (!(ie->ie_flags & IE_SOFT))
return (EINVAL);
} else {
error = intr_event_create(&ie, NULL, IE_SOFT, 0,
NULL, NULL, NULL, swi_assign_cpu, "swi%d:", pri);
if (error)
return (error);
if (eventp != NULL)
*eventp = ie;
}
error = intr_event_add_handler(ie, name, NULL, handler, arg,
PI_SWI(pri), flags, cookiep);
return (error);
}
/*
* Schedule a software interrupt thread.
*/
void
swi_sched(void *cookie, int flags)
{
struct intr_handler *ih = (struct intr_handler *)cookie;
struct intr_event *ie = ih->ih_event;
struct intr_entropy entropy;
int error __unused;
CTR3(KTR_INTR, "swi_sched: %s %s need=%d", ie->ie_name, ih->ih_name,
ih->ih_need);
entropy.event = (uintptr_t)ih;
entropy.td = curthread;
random_harvest_queue(&entropy, sizeof(entropy), RANDOM_SWI);
/*
* 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.
*/
ih->ih_need = 1;
if (!(flags & SWI_DELAY)) {
VM_CNT_INC(v_soft);
error = intr_event_schedule_thread(ie);
KASSERT(error == 0, ("stray software interrupt"));
}
}
/*
* Remove a software interrupt handler. Currently this code does not
* remove the associated interrupt event if it becomes empty. Calling code
* may do so manually via intr_event_destroy(), but that's not really
* an optimal interface.
*/
int
swi_remove(void *cookie)
{
return (intr_event_remove_handler(cookie));
}
static void
intr_event_execute_handlers(struct proc *p, struct intr_event *ie)
{
struct intr_handler *ih, *ihn, *ihp;
ihp = NULL;
CK_SLIST_FOREACH_SAFE(ih, &ie->ie_handlers, ih_next, ihn) {
/*
* If this handler is marked for death, remove it from
* the list of handlers and wake up the sleeper.
*/
if (ih->ih_flags & IH_DEAD) {
mtx_lock(&ie->ie_lock);
if (ihp == NULL)
CK_SLIST_REMOVE_HEAD(&ie->ie_handlers, ih_next);
else
CK_SLIST_REMOVE_AFTER(ihp, ih_next);
ih->ih_flags &= ~IH_DEAD;
wakeup(ih);
mtx_unlock(&ie->ie_lock);
continue;
}
/*
* Now that we know that the current element won't be removed
* update the previous element.
*/
ihp = ih;
if ((ih->ih_flags & IH_CHANGED) != 0) {
mtx_lock(&ie->ie_lock);
ih->ih_flags &= ~IH_CHANGED;
wakeup(ih);
mtx_unlock(&ie->ie_lock);
}
/* Skip filter only handlers */
if (ih->ih_handler == NULL)
continue;
/* Skip suspended handlers */
if ((ih->ih_flags & IH_SUSP) != 0)
continue;
/*
* For software interrupt threads, we only execute
* handlers that have their need flag set. Hardware
* interrupt threads always invoke all of their handlers.
*
* ih_need can only be 0 or 1. Failed cmpset below
* means that there is no request to execute handlers,
* so a retry of the cmpset is not needed.
*/
if ((ie->ie_flags & IE_SOFT) != 0 &&
atomic_cmpset_int(&ih->ih_need, 1, 0) == 0)
continue;
/* Execute this handler. */
CTR6(KTR_INTR, "%s: pid %d exec %p(%p) for %s flg=%x",
__func__, p->p_pid, (void *)ih->ih_handler,
ih->ih_argument, ih->ih_name, ih->ih_flags);
if (!(ih->ih_flags & IH_MPSAFE))
mtx_lock(&Giant);
ih->ih_handler(ih->ih_argument);
if (!(ih->ih_flags & IH_MPSAFE))
mtx_unlock(&Giant);
}
}
static void
ithread_execute_handlers(struct proc *p, struct intr_event *ie)
{
/* Interrupt handlers should not sleep. */
if (!(ie->ie_flags & IE_SOFT))
THREAD_NO_SLEEPING();
intr_event_execute_handlers(p, ie);
if (!(ie->ie_flags & IE_SOFT))
THREAD_SLEEPING_OK();
/*
* Interrupt storm handling:
*
* If this interrupt source is currently storming, then throttle
* it to only fire the handler once per clock tick.
*
* If this interrupt source is not currently storming, but the
* number of back to back interrupts exceeds the storm threshold,
* then enter storming mode.
*/
if (intr_storm_threshold != 0 && ie->ie_count >= intr_storm_threshold &&
!(ie->ie_flags & IE_SOFT)) {
/* Report the message only once every second. */
if (ppsratecheck(&ie->ie_warntm, &ie->ie_warncnt, 1)) {
printf(
"interrupt storm detected on \"%s\"; throttling interrupt source\n",
ie->ie_name);
}
pause("istorm", 1);
} else
ie->ie_count++;
/*
* Now that all the handlers have had a chance to run, reenable
* the interrupt source.
*/
if (ie->ie_post_ithread != NULL)
ie->ie_post_ithread(ie->ie_source);
}
/*
* This is the main code for interrupt threads.
*/
static void
ithread_loop(void *arg)
{
struct intr_thread *ithd;
struct intr_event *ie;
struct thread *td;
struct proc *p;
int wake;
td = curthread;
p = td->td_proc;
ithd = (struct intr_thread *)arg;
KASSERT(ithd->it_thread == td,
("%s: ithread and proc linkage out of sync", __func__));
ie = ithd->it_event;
ie->ie_count = 0;
wake = 0;
/*
* 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) {
CTR3(KTR_INTR, "%s: pid %d (%s) exiting", __func__,
p->p_pid, td->td_name);
free(ithd, M_ITHREAD);
kthread_exit();
}
/*
* Service interrupts. If another interrupt arrives while
* we are running, it will set it_need to note that we
* should make another pass.
*
* The load_acq part of the following cmpset ensures
* that the load of ih_need in ithread_execute_handlers()
* is ordered after the load of it_need here.
*/
while (atomic_cmpset_acq_int(&ithd->it_need, 1, 0) != 0)
ithread_execute_handlers(p, ie);
WITNESS_WARN(WARN_PANIC, NULL, "suspending ithread");
mtx_assert(&Giant, MA_NOTOWNED);
/*
* 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.
*/
thread_lock(td);
if (atomic_load_acq_int(&ithd->it_need) == 0 &&
(ithd->it_flags & (IT_DEAD | IT_WAIT)) == 0) {
TD_SET_IWAIT(td);
ie->ie_count = 0;
mi_switch(SW_VOL | SWT_IWAIT, NULL);
}
if (ithd->it_flags & IT_WAIT) {
wake = 1;
ithd->it_flags &= ~IT_WAIT;
}
thread_unlock(td);
if (wake) {
wakeup(ithd);
wake = 0;
}
}
}
/*
* Main interrupt handling body.
*
* Input:
* o ie: the event connected to this interrupt.
* o frame: some archs (i.e. i386) pass a frame to some.
* handlers as their main argument.
* Return value:
* o 0: everything ok.
* o EINVAL: stray interrupt.
*/
int
intr_event_handle(struct intr_event *ie, struct trapframe *frame)
{
struct intr_handler *ih;
struct trapframe *oldframe;
struct thread *td;
int phase;
int ret;
bool filter, thread;
td = curthread;
#ifdef KSTACK_USAGE_PROF
intr_prof_stack_use(td, frame);
#endif
/* An interrupt with no event or handlers is a stray interrupt. */
if (ie == NULL || CK_SLIST_EMPTY(&ie->ie_handlers))
return (EINVAL);
/*
* Execute fast interrupt handlers directly.
* To support clock handlers, if a handler registers
* with a NULL argument, then we pass it a pointer to
* a trapframe as its argument.
*/
td->td_intr_nesting_level++;
filter = false;
thread = false;
ret = 0;
critical_enter();
oldframe = td->td_intr_frame;
td->td_intr_frame = frame;
phase = ie->ie_phase;
atomic_add_int(&ie->ie_active[phase], 1);
/*
* This fence is required to ensure that no later loads are
* re-ordered before the ie_active store.
*/
atomic_thread_fence_seq_cst();
CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) {
if ((ih->ih_flags & IH_SUSP) != 0)
continue;
if (ih->ih_filter == NULL) {
thread = true;
continue;
}
CTR4(KTR_INTR, "%s: exec %p(%p) for %s", __func__,
ih->ih_filter, ih->ih_argument == NULL ? frame :
ih->ih_argument, ih->ih_name);
if (ih->ih_argument == NULL)
ret = ih->ih_filter(frame);
else
ret = ih->ih_filter(ih->ih_argument);
KASSERT(ret == FILTER_STRAY ||
((ret & (FILTER_SCHEDULE_THREAD | FILTER_HANDLED)) != 0 &&
(ret & ~(FILTER_SCHEDULE_THREAD | FILTER_HANDLED)) == 0),
("%s: incorrect return value %#x from %s", __func__, ret,
ih->ih_name));
filter = filter || ret == FILTER_HANDLED;
/*
* Wrapper handler special handling:
*
* in some particular cases (like pccard and pccbb),
* the _real_ device handler is wrapped in a couple of
* functions - a filter wrapper and an ithread wrapper.
* In this case (and just in this case), the filter wrapper
* could ask the system to schedule the ithread and mask
* the interrupt source if the wrapped handler is composed
* of just an ithread handler.
*
* TODO: write a generic wrapper to avoid people rolling
* their own.
*/
if (!thread) {
if (ret == FILTER_SCHEDULE_THREAD)
thread = true;
}
}
atomic_add_rel_int(&ie->ie_active[phase], -1);
td->td_intr_frame = oldframe;
if (thread) {
if (ie->ie_pre_ithread != NULL)
ie->ie_pre_ithread(ie->ie_source);
} else {
if (ie->ie_post_filter != NULL)
ie->ie_post_filter(ie->ie_source);
}
/* Schedule the ithread if needed. */
if (thread) {
int error __unused;
error = intr_event_schedule_thread(ie);
KASSERT(error == 0, ("bad stray interrupt"));
}
critical_exit();
td->td_intr_nesting_level--;
#ifdef notyet
/* The interrupt is not aknowledged by any filter and has no ithread. */
if (!thread && !filter)
return (EINVAL);
#endif
return (0);
}
#ifdef DDB
/*
* Dump details about an interrupt handler
*/
static void
db_dump_intrhand(struct intr_handler *ih)
{
int comma;
db_printf("\t%-10s ", ih->ih_name);
switch (ih->ih_pri) {
case PI_REALTIME:
db_printf("CLK ");
break;
case PI_AV:
db_printf("AV ");
break;
case PI_TTY:
db_printf("TTY ");
break;
case PI_NET:
db_printf("NET ");
break;
case PI_DISK:
db_printf("DISK");
break;
case PI_DULL:
db_printf("DULL");
break;
default:
if (ih->ih_pri >= PI_SOFT)
db_printf("SWI ");
else
db_printf("%4u", ih->ih_pri);
break;
}
db_printf(" ");
if (ih->ih_filter != NULL) {
db_printf("[F]");
db_printsym((uintptr_t)ih->ih_filter, DB_STGY_PROC);
}
if (ih->ih_handler != NULL) {
if (ih->ih_filter != NULL)
db_printf(",");
db_printf("[H]");
db_printsym((uintptr_t)ih->ih_handler, DB_STGY_PROC);
}
db_printf("(%p)", ih->ih_argument);
if (ih->ih_need ||
(ih->ih_flags & (IH_EXCLUSIVE | IH_ENTROPY | IH_DEAD |
IH_MPSAFE)) != 0) {
db_printf(" {");
comma = 0;
if (ih->ih_flags & IH_EXCLUSIVE) {
if (comma)
db_printf(", ");
db_printf("EXCL");
comma = 1;
}
if (ih->ih_flags & IH_ENTROPY) {
if (comma)
db_printf(", ");
db_printf("ENTROPY");
comma = 1;
}
if (ih->ih_flags & IH_DEAD) {
if (comma)
db_printf(", ");
db_printf("DEAD");
comma = 1;
}
if (ih->ih_flags & IH_MPSAFE) {
if (comma)
db_printf(", ");
db_printf("MPSAFE");
comma = 1;
}
if (ih->ih_need) {
if (comma)
db_printf(", ");
db_printf("NEED");
}
db_printf("}");
}
db_printf("\n");
}
/*
* Dump details about a event.
*/
void
db_dump_intr_event(struct intr_event *ie, int handlers)
{
struct intr_handler *ih;
struct intr_thread *it;
int comma;
db_printf("%s ", ie->ie_fullname);
it = ie->ie_thread;
if (it != NULL)
db_printf("(pid %d)", it->it_thread->td_proc->p_pid);
else
db_printf("(no thread)");
if ((ie->ie_flags & (IE_SOFT | IE_ENTROPY | IE_ADDING_THREAD)) != 0 ||
(it != NULL && it->it_need)) {
db_printf(" {");
comma = 0;
if (ie->ie_flags & IE_SOFT) {
db_printf("SOFT");
comma = 1;
}
if (ie->ie_flags & IE_ENTROPY) {
if (comma)
db_printf(", ");
db_printf("ENTROPY");
comma = 1;
}
if (ie->ie_flags & IE_ADDING_THREAD) {
if (comma)
db_printf(", ");
db_printf("ADDING_THREAD");
comma = 1;
}
if (it != NULL && it->it_need) {
if (comma)
db_printf(", ");
db_printf("NEED");
}
db_printf("}");
}
db_printf("\n");
if (handlers)
CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next)
db_dump_intrhand(ih);
}
/*
* Dump data about interrupt handlers
*/
DB_SHOW_COMMAND(intr, db_show_intr)
{
struct intr_event *ie;
int all, verbose;
verbose = strchr(modif, 'v') != NULL;
all = strchr(modif, 'a') != NULL;
TAILQ_FOREACH(ie, &event_list, ie_list) {
if (!all && CK_SLIST_EMPTY(&ie->ie_handlers))
continue;
db_dump_intr_event(ie, verbose);
if (db_pager_quit)
break;
}
}
#endif /* DDB */
/*
* Start standard software interrupt threads
*/
static void
start_softintr(void *dummy)
{
if (swi_add(NULL, "vm", swi_vm, NULL, SWI_VM, INTR_MPSAFE, &vm_ih))
panic("died while creating vm swi ithread");
}
SYSINIT(start_softintr, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softintr,
NULL);
/*
* Sysctls used by systat and others: hw.intrnames and hw.intrcnt.
* The data for this machine dependent, and the declarations are in machine
* dependent code. The layout of intrnames and intrcnt however is machine
* independent.
*
* We do not know the length of intrcnt and intrnames at compile time, so
* calculate things at run time.
*/
static int
sysctl_intrnames(SYSCTL_HANDLER_ARGS)
{
return (sysctl_handle_opaque(oidp, intrnames, sintrnames, req));
}
SYSCTL_PROC(_hw, OID_AUTO, intrnames, CTLTYPE_OPAQUE | CTLFLAG_RD,
NULL, 0, sysctl_intrnames, "", "Interrupt Names");
static int
sysctl_intrcnt(SYSCTL_HANDLER_ARGS)
{
#ifdef SCTL_MASK32
uint32_t *intrcnt32;
unsigned i;
int error;
if (req->flags & SCTL_MASK32) {
if (!req->oldptr)
return (sysctl_handle_opaque(oidp, NULL, sintrcnt / 2, req));
intrcnt32 = malloc(sintrcnt / 2, M_TEMP, M_NOWAIT);
if (intrcnt32 == NULL)
return (ENOMEM);
for (i = 0; i < sintrcnt / sizeof (u_long); i++)
intrcnt32[i] = intrcnt[i];
error = sysctl_handle_opaque(oidp, intrcnt32, sintrcnt / 2, req);
free(intrcnt32, M_TEMP);
return (error);
}
#endif
return (sysctl_handle_opaque(oidp, intrcnt, sintrcnt, req));
}
SYSCTL_PROC(_hw, OID_AUTO, intrcnt, CTLTYPE_OPAQUE | CTLFLAG_RD,
NULL, 0, sysctl_intrcnt, "", "Interrupt Counts");
#ifdef DDB
/*
* DDB command to dump the interrupt statistics.
*/
DB_SHOW_COMMAND(intrcnt, db_show_intrcnt)
{
u_long *i;
char *cp;
u_int j;
cp = intrnames;
j = 0;
for (i = intrcnt; j < (sintrcnt / sizeof(u_long)) && !db_pager_quit;
i++, j++) {
if (*cp == '\0')
break;
if (*i != 0)
db_printf("%s\t%lu\n", cp, *i);
cp += strlen(cp) + 1;
}
}
#endif