x86: use RCU to protect the IRQ handlers list
Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>
diff --git a/kern/arch/x86/trap.c b/kern/arch/x86/trap.c
index 15fbdc8..16cdc5c 100644
--- a/kern/arch/x86/trap.c
+++ b/kern/arch/x86/trap.c
@@ -34,7 +34,7 @@
pseudodesc_t idt_pd;
/* interrupt handler table, each element is a linked list of handlers for a
- * given IRQ. Modification requires holding the lock (TODO: RCU) */
+ * given IRQ. Modification requires holding the lock. */
struct irq_handler *irq_handlers[NUM_IRQS];
spinlock_t irq_handler_wlock = SPINLOCK_INITIALIZER_IRQSAVE;
@@ -717,8 +717,8 @@
if (hw_tf->tf_trapno != 65) /* qemu serial tends to get this one */
printd("Incoming IRQ, ISR: %d on core %d\n", hw_tf->tf_trapno,
core_id());
- /* TODO: RCU read lock */
- irq_h = irq_handlers[hw_tf->tf_trapno];
+ rcu_read_lock();
+ irq_h = rcu_dereference(irq_handlers[hw_tf->tf_trapno]);
if (!irq_h) {
warn_once("Received IRQ %d, had no handler registered!",
hw_tf->tf_trapno);
@@ -735,7 +735,7 @@
enable_irq();
while (irq_h) {
irq_h->isr(hw_tf, irq_h->data);
- irq_h = irq_h->next;
+ irq_h = rcu_dereference(irq_h->next);
}
// if we're a general purpose IPI function call, down the cpu_list
extern handler_wrapper_t handler_wrappers[NUM_HANDLER_WRAPPERS];
@@ -745,9 +745,11 @@
.cpu_list);
disable_irq();
/* Keep in sync with ipi_is_pending */
- irq_handlers[hw_tf->tf_trapno]->eoi(hw_tf->tf_trapno);
+ irq_h = rcu_dereference(irq_handlers[hw_tf->tf_trapno]);
+ irq_h->eoi(hw_tf->tf_trapno);
/* Fall-through */
out_no_eoi:
+ rcu_read_unlock();
dec_irq_depth(pcpui);
if (!in_irq_ctx(pcpui))
__set_cpu_state(pcpui, CPU_STATE_KERNEL);
@@ -801,11 +803,9 @@
irq_h->isr = handler;
irq_h->data = irq_arg;
irq_h->apic_vector = vector;
- /* RCU write lock */
spin_lock_irqsave(&irq_handler_wlock);
irq_h->next = irq_handlers[vector];
- wmb(); /* make sure irq_h is done before publishing to readers */
- irq_handlers[vector] = irq_h;
+ rcu_assign_pointer(irq_handlers[vector], irq_h);
spin_unlock_irqsave(&irq_handler_wlock);
/* Most IRQs other than the BusIPI should need their irq unmasked.
* Might need to pass the irq_h, in case unmask needs more info.
