linux-kernel - [PATCH v2 5/8] irqbypass: Use paired consumer/producer to disconnect during unregister

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Message-ID: <20250516230734.2564775-6-seanjc@google.com>
Date: Fri, 16 May 2025 16:07:31 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Alex Williamson <alex.williamson@...hat.com>
Cc: kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Kevin Tian <kevin.tian@...el.com>, Oliver Upton <oliver.upton@...ux.dev>, 
	David Matlack <dmatlack@...gle.com>, Like Xu <like.xu.linux@...il.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yong He <alexyonghe@...cent.com>
Subject: [PATCH v2 5/8] irqbypass: Use paired consumer/producer to disconnect
 during unregister

Use the paired consumer/producer information to disconnect IRQ bypass
producers/consumers in O(1) time (ignoring the cost of __disconnect()).

Reviewed-by: Kevin Tian <kevin.tian@...el.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 virt/lib/irqbypass.c | 48 ++++++++------------------------------------
 1 file changed, 8 insertions(+), 40 deletions(-)

diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
index fdbf7ecc0c21..6a183459dc44 100644
--- a/virt/lib/irqbypass.c
+++ b/virt/lib/irqbypass.c
@@ -138,32 +138,16 @@ EXPORT_SYMBOL_GPL(irq_bypass_register_producer);
  */
 void irq_bypass_unregister_producer(struct irq_bypass_producer *producer)
 {
-	struct irq_bypass_producer *tmp;
-	struct irq_bypass_consumer *consumer;
-
 	if (!producer->eventfd)
 		return;
 
 	mutex_lock(&lock);
 
-	list_for_each_entry(tmp, &producers, node) {
-		if (tmp->eventfd != producer->eventfd)
-			continue;
+	if (producer->consumer)
+		__disconnect(producer, producer->consumer);
 
-		list_for_each_entry(consumer, &consumers, node) {
-			if (consumer->eventfd == producer->eventfd) {
-				WARN_ON_ONCE(producer->consumer != consumer);
-				__disconnect(producer, consumer);
-				break;
-			}
-		}
-
-		producer->eventfd = NULL;
-		list_del(&producer->node);
-		break;
-	}
-
-	WARN_ON_ONCE(producer->eventfd);
+	producer->eventfd = NULL;
+	list_del(&producer->node);
 	mutex_unlock(&lock);
 }
 EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer);
@@ -228,32 +212,16 @@ EXPORT_SYMBOL_GPL(irq_bypass_register_consumer);
  */
 void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
 {
-	struct irq_bypass_consumer *tmp;
-	struct irq_bypass_producer *producer;
-
 	if (!consumer->eventfd)
 		return;
 
 	mutex_lock(&lock);
 
-	list_for_each_entry(tmp, &consumers, node) {
-		if (tmp != consumer)
-			continue;
+	if (consumer->producer)
+		__disconnect(consumer->producer, consumer);
 
-		list_for_each_entry(producer, &producers, node) {
-			if (producer->eventfd == consumer->eventfd) {
-				WARN_ON_ONCE(consumer->producer != producer);
-				__disconnect(producer, consumer);
-				break;
-			}
-		}
-
-		consumer->eventfd = NULL;
-		list_del(&consumer->node);
-		break;
-	}
-
-	WARN_ON_ONCE(consumer->eventfd);
+	consumer->eventfd = NULL;
+	list_del(&consumer->node);
 	mutex_unlock(&lock);
 }
 EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer);
-- 
2.49.0.1112.g889b7c5bd8-goog