void
cpu_lwp_exit(void)
{
struct thread *td = curthread;
struct pcb *pcb;
npxexit();
pcb = td->td_pcb;
/* Some i386 functionality was dropped */
KKASSERT(pcb->pcb_ext == NULL);
/*
* disable all hardware breakpoints
*/
if (pcb->pcb_flags & PCB_DBREGS) {
reset_dbregs();
pcb->pcb_flags &= ~PCB_DBREGS;
}
td->td_gd->gd_cnt.v_swtch++;
crit_enter_quick(td);
if (td->td_flags & TDF_TSLEEPQ)
tsleep_remove(td);
lwkt_deschedule_self(td);
lwkt_remove_tdallq(td);
cpu_thread_exit();
}
/*
* Userland override of lwkt_exit. The only difference is
* the manipulation of gd->gd_num_threads;
*/
void
lwkt_exit(void)
{
thread_t td = curthread;
globaldata_t gd = mycpu;
if (td->td_flags & TDF_VERBOSE)
printf("kthread %p %s has exited\n", td, td->td_comm);
crit_enter();
lwkt_deschedule_self(td);
++gd->gd_tdfreecount;
if (td->td_flags & TDF_SYSTHREAD)
--gd->gd_sys_threads;
--gd->gd_num_threads;
TAILQ_INSERT_TAIL(&gd->gd_tdfreeq, td, td_threadq);
cpu_thread_exit();
}
void
cpu_lwp_exit(void)
{
struct thread *td = curthread;
struct pcb *pcb;
struct pcb_ext *ext;
/*
* If we were using a private TSS do a forced-switch to ourselves
* to switch back to the common TSS before freeing it.
*/
pcb = td->td_pcb;
if ((ext = pcb->pcb_ext) != NULL) {
crit_enter();
pcb->pcb_ext = NULL;
lwkt_switch_return(td->td_switch(td));
crit_exit();
kmem_free(&kernel_map, (vm_offset_t)ext, ctob(IOPAGES + 1));
}
user_ldt_free(pcb);
if (pcb->pcb_flags & PCB_DBREGS) {
/*
* disable all hardware breakpoints
*/
reset_dbregs();
pcb->pcb_flags &= ~PCB_DBREGS;
}
td->td_gd->gd_cnt.v_swtch++;
crit_enter_quick(td);
if (td->td_flags & TDF_TSLEEPQ)
tsleep_remove(td);
lwkt_deschedule_self(td);
lwkt_remove_tdallq(td);
cpu_thread_exit();
}
/*
* Panic is called on unresolvable fatal errors. It prints "panic: mesg",
* and then reboots. If we are called twice, then we avoid trying to sync
* the disks as this often leads to recursive panics.
*/
void
panic(const char *fmt, ...)
{
int bootopt, newpanic;
globaldata_t gd = mycpu;
thread_t td = gd->gd_curthread;
__va_list ap;
static char buf[256];
#ifdef SMP
/*
* If a panic occurs on multiple cpus before the first is able to
* halt the other cpus, only one cpu is allowed to take the panic.
* Attempt to be verbose about this situation but if the kprintf()
* itself panics don't let us overrun the kernel stack.
*
* Be very nasty about descheduling our thread at the lowest
* level possible in an attempt to freeze the thread without
* inducing further panics.
*
* Bumping gd_trap_nesting_level will also bypass assertions in
* lwkt_switch() and allow us to switch away even if we are a
* FAST interrupt or IPI.
*
* The setting of panic_cpu_gd also determines how kprintf()
* spin-locks itself. DDB can set panic_cpu_gd as well.
*/
for (;;) {
globaldata_t xgd = panic_cpu_gd;
/*
* Someone else got the panic cpu
*/
if (xgd && xgd != gd) {
crit_enter();
++mycpu->gd_trap_nesting_level;
if (mycpu->gd_trap_nesting_level < 25) {
kprintf("SECONDARY PANIC ON CPU %d THREAD %p\n",
mycpu->gd_cpuid, td);
}
td->td_release = NULL; /* be a grinch */
for (;;) {
lwkt_deschedule_self(td);
lwkt_switch();
}
/* NOT REACHED */
/* --mycpu->gd_trap_nesting_level */
/* crit_exit() */
}
/*
* Reentrant panic
*/
if (xgd && xgd == gd)
break;
/*
* We got it
*/
if (atomic_cmpset_ptr(&panic_cpu_gd, NULL, gd))
break;
}
#else
panic_cpu_gd = gd;
#endif
/*
* Try to get the system into a working state. Save information
* we are about to destroy.
*/
kvcreinitspin();
if (panicstr == NULL) {
bcopy(td->td_toks_array, panic_tokens, sizeof(panic_tokens));
panic_tokens_count = td->td_toks_stop - &td->td_toks_base;
}
lwkt_relalltokens(td);
td->td_toks_stop = &td->td_toks_base;
/*
* Setup
*/
bootopt = RB_AUTOBOOT | RB_DUMP;
if (sync_on_panic == 0)
bootopt |= RB_NOSYNC;
newpanic = 0;
if (panicstr) {
bootopt |= RB_NOSYNC;
} else {
panicstr = fmt;
newpanic = 1;
}
/*
* Format the panic string.
*/
__va_start(ap, fmt);
kvsnprintf(buf, sizeof(buf), fmt, ap);
if (panicstr == fmt)
panicstr = buf;
__va_end(ap);
kprintf("panic: %s\n", buf);
#ifdef SMP
/* two separate prints in case of an unmapped page and trap */
kprintf("cpuid = %d\n", mycpu->gd_cpuid);
#endif
#if (NGPIO > 0) && defined(ERROR_LED_ON_PANIC)
led_switch("error", 1);
#endif
#if defined(WDOG_DISABLE_ON_PANIC) && defined(WATCHDOG_ENABLE)
wdog_disable();
#endif
/*
* Enter the debugger or fall through & dump. Entering the
* debugger will stop cpus. If not entering the debugger stop
* cpus here.
*/
#if defined(DDB)
if (newpanic && trace_on_panic)
print_backtrace(-1);
if (debugger_on_panic)
Debugger("panic");
else
#endif
#ifdef SMP
if (newpanic)
stop_cpus(mycpu->gd_other_cpus);
#else
;
#endif
boot(bootopt);
}
/*
* This procedure is the main loop of our per-cpu helper thread. The
* sc->isrunning flag prevents us from racing hardclock_softtick() and
* a critical section is sufficient to interlock sc->curticks and protect
* us from remote IPI's / list removal.
*
* The thread starts with the MP lock released and not in a critical
* section. The loop itself is MP safe while individual callbacks
* may or may not be, so we obtain or release the MP lock as appropriate.
*/
static void
softclock_handler(void *arg)
{
softclock_pcpu_t sc;
struct callout *c;
struct callout_tailq *bucket;
void (*c_func)(void *);
void *c_arg;
int mpsafe = 1;
/*
* Run the callout thread at the same priority as other kernel
* threads so it can be round-robined.
*/
/*lwkt_setpri_self(TDPRI_SOFT_NORM);*/
sc = arg;
crit_enter();
loop:
while (sc->softticks != (int)(sc->curticks + 1)) {
bucket = &sc->callwheel[sc->softticks & callwheelmask];
for (c = TAILQ_FIRST(bucket); c; c = sc->next) {
if (c->c_time != sc->softticks) {
sc->next = TAILQ_NEXT(c, c_links.tqe);
continue;
}
if (c->c_flags & CALLOUT_MPSAFE) {
if (mpsafe == 0) {
mpsafe = 1;
rel_mplock();
}
} else {
/*
* The request might be removed while we
* are waiting to get the MP lock. If it
* was removed sc->next will point to the
* next valid request or NULL, loop up.
*/
if (mpsafe) {
mpsafe = 0;
sc->next = c;
get_mplock();
if (c != sc->next)
continue;
}
}
sc->next = TAILQ_NEXT(c, c_links.tqe);
TAILQ_REMOVE(bucket, c, c_links.tqe);
sc->running = c;
c_func = c->c_func;
c_arg = c->c_arg;
c->c_func = NULL;
KKASSERT(c->c_flags & CALLOUT_DID_INIT);
c->c_flags &= ~CALLOUT_PENDING;
crit_exit();
c_func(c_arg);
crit_enter();
sc->running = NULL;
/* NOTE: list may have changed */
}
++sc->softticks;
}
sc->isrunning = 0;
lwkt_deschedule_self(&sc->thread); /* == curthread */
lwkt_switch();
goto loop;
/* NOT REACHED */
}
/*
* This procedure is the main loop of our per-cpu helper thread. The
* sc->isrunning flag prevents us from racing hardclock_softtick() and
* a critical section is sufficient to interlock sc->curticks and protect
* us from remote IPI's / list removal.
*
* The thread starts with the MP lock released and not in a critical
* section. The loop itself is MP safe while individual callbacks
* may or may not be, so we obtain or release the MP lock as appropriate.
*/
static void
softclock_handler(void *arg)
{
softclock_pcpu_t sc;
struct callout *c;
struct callout_tailq *bucket;
struct callout slotimer;
int mpsafe = 1;
int flags;
/*
* Setup pcpu slow clocks which we want to run from the callout
* thread.
*/
callout_init_mp(&slotimer);
callout_reset(&slotimer, hz * 10, slotimer_callback, &slotimer);
/*
* Run the callout thread at the same priority as other kernel
* threads so it can be round-robined.
*/
/*lwkt_setpri_self(TDPRI_SOFT_NORM);*/
/*
* Loop critical section against ipi operations to this cpu.
*/
sc = arg;
crit_enter();
loop:
while (sc->softticks != (int)(sc->curticks + 1)) {
bucket = &sc->callwheel[sc->softticks & cwheelmask];
for (c = TAILQ_FIRST(bucket); c; c = sc->next) {
if (c->c_time != sc->softticks) {
sc->next = TAILQ_NEXT(c, c_links.tqe);
continue;
}
flags = c->c_flags;
if (flags & CALLOUT_MPSAFE) {
if (mpsafe == 0) {
mpsafe = 1;
rel_mplock();
}
} else {
/*
* The request might be removed while we
* are waiting to get the MP lock. If it
* was removed sc->next will point to the
* next valid request or NULL, loop up.
*/
if (mpsafe) {
mpsafe = 0;
sc->next = c;
get_mplock();
if (c != sc->next)
continue;
}
}
/*
* Queue protection only exists while we hold the
* critical section uninterrupted.
*
* Adjust sc->next when removing (c) from the queue,
* note that an IPI on this cpu may make further
* adjustments to sc->next.
*/
sc->next = TAILQ_NEXT(c, c_links.tqe);
TAILQ_REMOVE(bucket, c, c_links.tqe);
KASSERT((c->c_flags & CALLOUT_ARMED) &&
(c->c_flags & CALLOUT_PENDING) &&
CALLOUT_FLAGS_TO_CPU(c->c_flags) ==
mycpu->gd_cpuid,
("callout %p: bad flags %08x", c, c->c_flags));
/*
* Once CALLOUT_PENDING is cleared, sc->running
* protects the callout structure's existance but
* only until we call c_func(). A callout_stop()
* or callout_reset() issued from within c_func()
* will not block. The callout can also be kfree()d
* by c_func().
*
* We set EXECUTED before calling c_func() so a
* callout_stop() issued from within c_func() returns
* the correct status.
*/
if ((flags & (CALLOUT_AUTOLOCK | CALLOUT_ACTIVE)) ==
(CALLOUT_AUTOLOCK | CALLOUT_ACTIVE)) {
void (*c_func)(void *);
void *c_arg;
struct lock *c_lk;
int error;
/*
* NOTE: sc->running must be set prior to
* CALLOUT_PENDING being cleared to
* avoid missed CANCELs and *_stop()
* races.
*/
sc->running = (intptr_t)c;
c_func = c->c_func;
c_arg = c->c_arg;
c_lk = c->c_lk;
c->c_func = NULL;
KKASSERT(c->c_flags & CALLOUT_DID_INIT);
flags = callout_unpend_disarm(c);
error = lockmgr(c_lk, LK_EXCLUSIVE |
LK_CANCELABLE);
if (error == 0) {
atomic_set_int(&c->c_flags,
CALLOUT_EXECUTED);
crit_exit();
c_func(c_arg);
crit_enter();
lockmgr(c_lk, LK_RELEASE);
}
} else if (flags & CALLOUT_ACTIVE) {
void (*c_func)(void *);
void *c_arg;
sc->running = (intptr_t)c;
c_func = c->c_func;
c_arg = c->c_arg;
c->c_func = NULL;
KKASSERT(c->c_flags & CALLOUT_DID_INIT);
flags = callout_unpend_disarm(c);
atomic_set_int(&c->c_flags, CALLOUT_EXECUTED);
crit_exit();
c_func(c_arg);
crit_enter();
} else {
flags = callout_unpend_disarm(c);
}
/*
* Read and clear sc->running. If bit 0 was set,
* a callout_stop() is likely blocked waiting for
* the callback to complete.
*
* The sigclear above also cleared CALLOUT_WAITING
* and returns the contents of flags prior to clearing
* any bits.
*
* Interlock wakeup any _stop's waiting on us. Note
* that once c_func() was called, the callout
* structure (c) pointer may no longer be valid. It
* can only be used for the wakeup.
*/
if ((atomic_readandclear_ptr(&sc->running) & 1) ||
(flags & CALLOUT_WAITING)) {
wakeup(c);
}
/* NOTE: list may have changed */
}
++sc->softticks;
}
/*
* Don't leave us holding the MP lock when we deschedule ourselves.
*/
if (mpsafe == 0) {
mpsafe = 1;
rel_mplock();
}
sc->isrunning = 0;
lwkt_deschedule_self(&sc->thread); /* == curthread */
lwkt_switch();
goto loop;
/* NOT REACHED */
}
