/*
* Wait for a grace period to elapse. But it is illegal to invoke
* synchronize_sched() from within an RCU read-side critical section.
* Therefore, any legal call to synchronize_sched() is a quiescent
* state, and so on a UP system, synchronize_sched() need do nothing.
* Ditto for synchronize_rcu_bh(). (But Lai Jiangshan points out the
* benefits of doing might_sleep() to reduce latency.)
*
* Cool, huh? (Due to Josh Triplett.)
*
* But we want to make this a static inline later. The cond_resched()
* currently makes this problematic.
*/
void synchronize_sched(void)
{
RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
lock_is_held(&rcu_lock_map) ||
lock_is_held(&rcu_sched_lock_map),
"Illegal synchronize_sched() in RCU read-side critical section");
cond_resched();
}
struct noise_keypair *wg_noise_keypair_get(struct noise_keypair *keypair)
{
RCU_LOCKDEP_WARN(!rcu_read_lock_bh_held(),
"Taking noise keypair reference without holding the RCU BH read lock");
if (unlikely(!keypair || !kref_get_unless_zero(&keypair->refcount)))
return NULL;
return keypair;
}
int notrace notify_die(enum die_val val, const char *str,
struct pt_regs *regs, long err, int trap, int sig)
{
struct die_args args = {
.regs = regs,
.str = str,
.err = err,
.trapnr = trap,
.signr = sig,
};
RCU_LOCKDEP_WARN(!rcu_is_watching(),
"notify_die called but RCU thinks we're quiescent");
return atomic_notifier_call_chain(&die_chain, val, &args);
}
/*
* Helper function for synchronize_srcu() and synchronize_srcu_expedited().
*/
static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
{
struct rcu_synchronize rcu;
struct rcu_head *head = &rcu.head;
bool done = false;
RCU_LOCKDEP_WARN(lock_is_held(&sp->dep_map) ||
lock_is_held(&rcu_bh_lock_map) ||
lock_is_held(&rcu_lock_map) ||
lock_is_held(&rcu_sched_lock_map),
"Illegal synchronize_srcu() in same-type SRCU (or in RCU) read-side critical section");
might_sleep();
init_completion(&rcu.completion);
head->next = NULL;
head->func = wakeme_after_rcu;
spin_lock_irq(&sp->queue_lock);
smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */
if (!sp->running) {
/* steal the processing owner */
sp->running = true;
rcu_batch_queue(&sp->batch_check0, head);
spin_unlock_irq(&sp->queue_lock);
srcu_advance_batches(sp, trycount);
if (!rcu_batch_empty(&sp->batch_done)) {
BUG_ON(sp->batch_done.head != head);
rcu_batch_dequeue(&sp->batch_done);
done = true;
}
/* give the processing owner to work_struct */
srcu_reschedule(sp);
} else {
rcu_batch_queue(&sp->batch_queue, head);
spin_unlock_irq(&sp->queue_lock);
}
if (!done) {
wait_for_completion(&rcu.completion);
smp_mb(); /* Caller's later accesses after GP. */
}
}
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*/
__visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
struct irq_desc * desc;
/* high bit used in ret_from_ code */
unsigned vector = ~regs->orig_ax;
/*
* NB: Unlike exception entries, IRQ entries do not reliably
* handle context tracking in the low-level entry code. This is
* because syscall entries execute briefly with IRQs on before
* updating context tracking state, so we can take an IRQ from
* kernel mode with CONTEXT_USER. The low-level entry code only
* updates the context if we came from user mode, so we won't
* switch to CONTEXT_KERNEL. We'll fix that once the syscall
* code is cleaned up enough that we can cleanly defer enabling
* IRQs.
*/
entering_irq();
/* entering_irq() tells RCU that we're not quiescent. Check it. */
RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU");
desc = __this_cpu_read(vector_irq[vector]);
if (!handle_irq(desc, regs)) {
ack_APIC_irq();
if (desc != VECTOR_RETRIGGERED) {
pr_emerg_ratelimited("%s: %d.%d No irq handler for vector\n",
__func__, smp_processor_id(),
vector);
} else {
__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
}
}
exiting_irq();
set_irq_regs(old_regs);
return 1;
}
void rcu_sync_lockdep_assert(struct rcu_sync *rsp)
{
RCU_LOCKDEP_WARN(!gp_ops[rsp->gp_type].held(),
"suspicious rcu_sync_is_idle() usage");
}
