/*
* lwkt_thread_replyport() - Backend to lwkt_replymsg()
*
* Called with the reply port as an argument but in the context of the
* original target port. Completion must occur on the target port's
* cpu.
*
* The critical section protects us from IPIs on the this CPU.
*/
static
void
lwkt_thread_replyport(lwkt_port_t port, lwkt_msg_t msg)
{
int flags;
KKASSERT((msg->ms_flags & (MSGF_DONE|MSGF_QUEUED|MSGF_INTRANSIT)) == 0);
if (msg->ms_flags & MSGF_SYNC) {
/*
* If a synchronous completion has been requested, just wakeup
* the message without bothering to queue it to the target port.
*
* Assume the target thread is non-preemptive, so no critical
* section is required.
*/
if (port->mpu_td->td_gd == mycpu) {
crit_enter();
flags = msg->ms_flags;
cpu_sfence();
msg->ms_flags |= MSGF_DONE | MSGF_REPLY;
if (port->mp_flags & MSGPORTF_WAITING)
_lwkt_schedule_msg(port->mpu_td, flags);
crit_exit();
} else {
#ifdef INVARIANTS
atomic_set_int(&msg->ms_flags, MSGF_INTRANSIT);
#endif
atomic_set_int(&msg->ms_flags, MSGF_REPLY);
lwkt_send_ipiq(port->mpu_td->td_gd,
(ipifunc1_t)lwkt_thread_replyport_remote, msg);
}
} else {
/*
* If an asynchronous completion has been requested the message
* must be queued to the reply port.
*
* A critical section is required to interlock the port queue.
*/
if (port->mpu_td->td_gd == mycpu) {
crit_enter();
_lwkt_enqueue_reply(port, msg);
if (port->mp_flags & MSGPORTF_WAITING)
_lwkt_schedule_msg(port->mpu_td, msg->ms_flags);
crit_exit();
} else {
#ifdef INVARIANTS
atomic_set_int(&msg->ms_flags, MSGF_INTRANSIT);
#endif
atomic_set_int(&msg->ms_flags, MSGF_REPLY);
lwkt_send_ipiq(port->mpu_td->td_gd,
(ipifunc1_t)lwkt_thread_replyport_remote, msg);
}
}
}
static void
sched_ithd_intern(struct intr_info *info)
{
++info->i_count;
if (info->i_state != ISTATE_NOTHREAD) {
if (info->i_reclist == NULL) {
report_stray_interrupt(info, "sched_ithd");
} else {
#ifdef SMP
if (info->i_thread.td_gd == mycpu) {
if (info->i_running == 0) {
info->i_running = 1;
if (info->i_state != ISTATE_LIVELOCKED)
lwkt_schedule(&info->i_thread); /* MIGHT PREEMPT */
}
} else {
lwkt_send_ipiq(info->i_thread.td_gd, sched_ithd_remote, info);
}
#else
if (info->i_running == 0) {
info->i_running = 1;
if (info->i_state != ISTATE_LIVELOCKED)
lwkt_schedule(&info->i_thread); /* MIGHT PREEMPT */
}
#endif
}
} else {
report_stray_interrupt(info, "sched_ithd");
}
}
static
int
lwkt_thread_putport(lwkt_port_t port, lwkt_msg_t msg)
{
KKASSERT((msg->ms_flags & (MSGF_DONE | MSGF_REPLY)) == 0);
msg->ms_target_port = port;
if (port->mpu_td->td_gd == mycpu) {
crit_enter();
_lwkt_pushmsg(port, msg);
if (port->mp_flags & MSGPORTF_WAITING)
_lwkt_schedule_msg(port->mpu_td, msg->ms_flags);
crit_exit();
} else {
#ifdef INVARIANTS
/*
* Cleanup.
*
* An atomic op is needed on ms_flags vs originator. Also
* note that the originator might be using a different type
* of msgport.
*/
atomic_set_int(&msg->ms_flags, MSGF_INTRANSIT);
#endif
lwkt_send_ipiq(port->mpu_td->td_gd,
(ipifunc1_t)lwkt_thread_putport_remote, msg);
}
return (EASYNC);
}
/*
* lwkt_thread_putport() - Backend to lwkt_beginmsg()
*
* Called with the target port as an argument but in the context of the
* reply port. This function always implements an asynchronous put to
* the target message port, and thus returns EASYNC.
*
* The message must already have cleared MSGF_DONE and MSGF_REPLY
*/
static
void
lwkt_thread_putport_remote(lwkt_msg_t msg)
{
lwkt_port_t port = msg->ms_target_port;
/*
* Chase any thread migration that occurs
*/
if (port->mpu_td->td_gd != mycpu) {
lwkt_send_ipiq(port->mpu_td->td_gd,
(ipifunc1_t)lwkt_thread_putport_remote, msg);
return;
}
/*
* An atomic op is needed on ms_flags vs originator. Also
* note that the originator might be using a different type
* of msgport.
*/
#ifdef INVARIANTS
KKASSERT(msg->ms_flags & MSGF_INTRANSIT);
atomic_clear_int(&msg->ms_flags, MSGF_INTRANSIT);
#endif
_lwkt_pushmsg(port, msg);
if (port->mp_flags & MSGPORTF_WAITING)
_lwkt_schedule_msg(port->mpu_td, msg->ms_flags);
}
/*
* This function completes reply processing for the default case in the
* context of the originating cpu.
*/
static
void
lwkt_thread_replyport_remote(lwkt_msg_t msg)
{
lwkt_port_t port = msg->ms_reply_port;
int flags;
/*
* Chase any thread migration that occurs
*/
if (port->mpu_td->td_gd != mycpu) {
lwkt_send_ipiq(port->mpu_td->td_gd,
(ipifunc1_t)lwkt_thread_replyport_remote, msg);
return;
}
/*
* Cleanup (in critical section, IPI on same cpu, atomic op not needed)
*/
#ifdef INVARIANTS
KKASSERT(msg->ms_flags & MSGF_INTRANSIT);
msg->ms_flags &= ~MSGF_INTRANSIT;
#endif
flags = msg->ms_flags;
if (msg->ms_flags & MSGF_SYNC) {
cpu_sfence();
msg->ms_flags |= MSGF_REPLY | MSGF_DONE;
} else {
_lwkt_enqueue_reply(port, msg);
}
if (port->mp_flags & MSGPORTF_WAITING)
_lwkt_schedule_msg(port->mpu_td, flags);
}
void
callout_reset_bycpu(struct callout *c, int to_ticks, void (*ftn)(void *),
void *arg, int cpuid)
{
KASSERT(cpuid >= 0 && cpuid < ncpus, ("invalid cpuid %d", cpuid));
#ifndef SMP
callout_reset(c, to_ticks, ftn, arg);
#else
if (cpuid == mycpuid) {
callout_reset(c, to_ticks, ftn, arg);
} else {
struct globaldata *target_gd;
struct callout_remote_arg rmt;
int seq;
rmt.c = c;
rmt.ftn = ftn;
rmt.arg = arg;
rmt.to_ticks = to_ticks;
target_gd = globaldata_find(cpuid);
seq = lwkt_send_ipiq(target_gd, callout_reset_ipi, &rmt);
lwkt_wait_ipiq(target_gd, seq);
}
#endif
}
void
lwkt_init_thread(thread_t td, void *stack, int stksize, int flags,
struct globaldata *gd)
{
bzero(td, sizeof(struct thread));
td->td_kstack = stack;
td->td_kstack_size = stksize;
td->td_flags |= flags;
td->td_gd = gd;
td->td_pri = TDPRI_KERN_DAEMON + TDPRI_CRIT;
lwkt_initport(&td->td_msgport, td);
cpu_init_thread(td);
if (td == &gd->gd_idlethread) {
TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
/* idle thread is not counted in gd_num_threads */
} else if (gd == mycpu) {
crit_enter();
TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
++gd->gd_num_threads;
if (td->td_flags & TDF_SYSTHREAD)
++gd->gd_sys_threads;
crit_exit();
} else {
lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
}
}
/*
* Schedule start call
*/
static void
lgue_start_schedule(struct ifnet *ifp)
{
#ifdef SMP
int cpu;
cpu = ifp->if_start_cpuid(ifp);
if (cpu != mycpuid)
lwkt_send_ipiq(globaldata_find(cpu), lgue_start_ipifunc, ifp);
else
#endif
lgue_start_ipifunc(ifp);
}
/*
* MPSAFE
*/
void
systimer_add(systimer_t info)
{
struct globaldata *gd = mycpu;
KKASSERT((info->flags & SYSTF_ONQUEUE) == 0);
crit_enter();
if (info->gd == gd) {
systimer_t scan1;
systimer_t scan2;
scan1 = TAILQ_FIRST(&gd->gd_systimerq);
if (scan1 == NULL || (int)(scan1->time - info->time) > 0) {
cputimer_intr_reload(info->time - sys_cputimer->count());
TAILQ_INSERT_HEAD(&gd->gd_systimerq, info, node);
} else {
scan2 = TAILQ_LAST(&gd->gd_systimerq, systimerq);
for (;;) {
if (scan1 == NULL) {
TAILQ_INSERT_TAIL(&gd->gd_systimerq, info, node);
break;
}
if ((int)(scan1->time - info->time) > 0) {
TAILQ_INSERT_BEFORE(scan1, info, node);
break;
}
if ((int)(scan2->time - info->time) <= 0) {
TAILQ_INSERT_AFTER(&gd->gd_systimerq, scan2, info, node);
break;
}
scan1 = TAILQ_NEXT(scan1, node);
scan2 = TAILQ_PREV(scan2, systimerq, node);
}
}
info->flags = (info->flags | SYSTF_ONQUEUE) & ~SYSTF_IPIRUNNING;
info->queue = &gd->gd_systimerq;
} else {
#ifdef SMP
KKASSERT((info->flags & SYSTF_IPIRUNNING) == 0);
info->flags |= SYSTF_IPIRUNNING;
lwkt_send_ipiq(info->gd, (ipifunc1_t)systimer_add, info);
#else
panic("systimer_add: bad gd in info %p", info);
#endif
}
crit_exit();
}
void
dump_reactivate_cpus(void)
{
#ifdef SMP
globaldata_t gd;
int cpu, seq;
#endif
dump_stop_usertds = 1;
need_user_resched();
#ifdef SMP
for (cpu = 0; cpu < ncpus; cpu++) {
gd = globaldata_find(cpu);
seq = lwkt_send_ipiq(gd, need_user_resched_remote, NULL);
lwkt_wait_ipiq(gd, seq);
}
restart_cpus(stopped_cpus);
#endif
}
/*
* Stop a running timer. WARNING! If called on a cpu other then the one
* the callout was started on this function will liveloop on its IPI to
* the target cpu to process the request. It is possible for the callout
* to execute in that case.
*
* WARNING! This function may be called from any cpu but the caller must
* serialize callout_stop() and callout_reset() calls on the passed
* structure regardless of cpu.
*
* WARNING! This routine may be called from an IPI
*
* WARNING! This function can return while it's c_func is still running
* in the callout thread, a secondary check may be needed.
* Use callout_stop_sync() to wait for any callout function to
* complete before returning, being sure that no deadlock is
* possible if you do.
*/
int
callout_stop(struct callout *c)
{
globaldata_t gd = mycpu;
globaldata_t tgd;
softclock_pcpu_t sc;
#ifdef INVARIANTS
if ((c->c_flags & CALLOUT_DID_INIT) == 0) {
callout_init(c);
kprintf(
"callout_stop(%p) from %p: callout was not initialized\n",
c, ((int **)&c)[-1]);
print_backtrace(-1);
}
#endif
crit_enter_gd(gd);
/*
* Don't attempt to delete a callout that's not on the queue. The
* callout may not have a cpu assigned to it. Callers do not have
* to be on the issuing cpu but must still serialize access to the
* callout structure.
*
* We are not cpu-localized here and cannot safely modify the
* flags field in the callout structure. Note that most of the
* time CALLOUT_ACTIVE will be 0 if CALLOUT_PENDING is also 0.
*
* If we race another cpu's dispatch of this callout it is possible
* for CALLOUT_ACTIVE to be set with CALLOUT_PENDING unset. This
* will cause us to fall through and synchronize with the other
* cpu.
*/
if ((c->c_flags & CALLOUT_PENDING) == 0) {
if ((c->c_flags & CALLOUT_ACTIVE) == 0) {
crit_exit_gd(gd);
return (0);
}
if (c->c_gd == NULL || c->c_gd == gd) {
c->c_flags &= ~CALLOUT_ACTIVE;
crit_exit_gd(gd);
return (0);
}
}
if ((tgd = c->c_gd) != gd) {
/*
* If the callout is owned by a different CPU we have to
* execute the function synchronously on the target cpu.
*/
int seq;
cpu_ccfence(); /* don't let tgd alias c_gd */
seq = lwkt_send_ipiq(tgd, (void *)callout_stop, c);
lwkt_wait_ipiq(tgd, seq);
} else {
/*
* If the callout is owned by the same CPU we can
* process it directly, but if we are racing our helper
* thread (sc->next), we have to adjust sc->next. The
* race is interlocked by a critical section.
*/
sc = &softclock_pcpu_ary[gd->gd_cpuid];
c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
if (sc->next == c)
sc->next = TAILQ_NEXT(c, c_links.tqe);
TAILQ_REMOVE(&sc->callwheel[c->c_time & callwheelmask],
c, c_links.tqe);
c->c_func = NULL;
}
crit_exit_gd(gd);
return (1);
}
/*
* Remote IPI for callout_reset_bycpu(). The operation is performed only
* on the 1->0 transition of the counter, otherwise there are callout_stop()s
* pending after us.
*
* The IPI counter and PENDING flags must be set atomically with the
* 1->0 transition. The ACTIVE flag was set prior to the ipi being
* sent and we do not want to race a caller on the original cpu trying
* to deactivate() the flag concurrent with our installation of the
* callout.
*/
static void
callout_reset_ipi(void *arg)
{
struct callout *c = arg;
globaldata_t gd = mycpu;
globaldata_t tgd;
int flags;
int nflags;
for (;;) {
flags = c->c_flags;
cpu_ccfence();
KKASSERT((flags & CALLOUT_IPI_MASK) > 0);
/*
* We should already be armed for our cpu, if armed to another
* cpu, chain the IPI. If for some reason we are not armed,
* we can arm ourselves.
*/
if (flags & CALLOUT_ARMED) {
if (CALLOUT_FLAGS_TO_CPU(flags) != gd->gd_cpuid) {
tgd = globaldata_find(
CALLOUT_FLAGS_TO_CPU(flags));
lwkt_send_ipiq(tgd, callout_reset_ipi, c);
return;
}
nflags = (flags & ~CALLOUT_EXECUTED);
} else {
nflags = (flags & ~(CALLOUT_CPU_MASK |
CALLOUT_EXECUTED)) |
CALLOUT_ARMED |
CALLOUT_CPU_TO_FLAGS(gd->gd_cpuid);
}
/*
* Decrement the IPI count, retain and clear the WAITING
* status, clear EXECUTED.
*
* NOTE: It is possible for the callout to already have been
* marked pending due to SMP races.
*/
nflags = nflags - 1;
if ((flags & CALLOUT_IPI_MASK) == 1) {
nflags &= ~(CALLOUT_WAITING | CALLOUT_EXECUTED);
nflags |= CALLOUT_PENDING;
}
if (atomic_cmpset_int(&c->c_flags, flags, nflags)) {
/*
* Only install the callout on the 1->0 transition
* of the IPI count, and only if PENDING was not
* already set. The latter situation should never
* occur but we check anyway.
*/
if ((flags & (CALLOUT_PENDING|CALLOUT_IPI_MASK)) == 1) {
softclock_pcpu_t sc;
sc = &softclock_pcpu_ary[gd->gd_cpuid];
c->c_time = sc->curticks + c->c_load;
TAILQ_INSERT_TAIL(
&sc->callwheel[c->c_time & cwheelmask],
c, c_links.tqe);
}
break;
}
/* retry */
cpu_pause();
}
/*
* Issue wakeup if requested.
*/
if (flags & CALLOUT_WAITING)
wakeup(c);
}
/*
* Setup a callout to run on the specified cpu. Should generally be used
* to run a callout on a specific cpu which does not nominally change.
*/
void
callout_reset_bycpu(struct callout *c, int to_ticks, void (*ftn)(void *),
void *arg, int cpuid)
{
globaldata_t gd;
globaldata_t tgd;
#ifdef INVARIANTS
if ((c->c_flags & CALLOUT_DID_INIT) == 0) {
callout_init(c);
kprintf(
"callout_reset(%p) from %p: callout was not initialized\n",
c, ((int **)&c)[-1]);
print_backtrace(-1);
}
#endif
gd = mycpu;
crit_enter_gd(gd);
tgd = globaldata_find(cpuid);
/*
* Our cpu must temporarily gain ownership of the callout and cancel
* anything still running, which is complex. The easiest way to do
* it is to issue a callout_stop().
*
* Clearing bits on flags (vs nflags) is a way to guarantee they were
* not previously set, by forcing the atomic op to fail. The callout
* must not be pending or armed after the stop_sync, if it is we have
* to loop up and stop_sync() again.
*/
for (;;) {
int flags;
int nflags;
callout_stop_sync(c);
flags = c->c_flags & ~(CALLOUT_PENDING | CALLOUT_ARMED);
nflags = (flags & ~(CALLOUT_CPU_MASK |
CALLOUT_EXECUTED)) |
CALLOUT_CPU_TO_FLAGS(tgd->gd_cpuid) |
CALLOUT_ARMED |
CALLOUT_ACTIVE;
nflags = nflags + 1; /* bump IPI count */
if (atomic_cmpset_int(&c->c_flags, flags, nflags))
break;
cpu_pause();
}
/*
* Even though we are not the cpu that now owns the callout, our
* bumping of the IPI count (and in a situation where the callout is
* not queued to the callwheel) will prevent anyone else from
* depending on or acting on the contents of the callout structure.
*/
if (to_ticks <= 0)
to_ticks = 1;
c->c_arg = arg;
c->c_func = ftn;
c->c_load = to_ticks; /* IPI will add curticks */
lwkt_send_ipiq(tgd, callout_reset_ipi, c);
crit_exit_gd(gd);
}
