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
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);
}
