[PATCH 5.12 090/296] Revert "irqbypass: do not start cons/prod when failed connect"

[Greg Kroah-Hartman]

From: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>

commit e44b49f623c77bee7451f1a82ccfb969c1028ae2 upstream.

This reverts commit a979a6aa009f3c99689432e0cdb5402a4463fb88.

The reverted commit may cause VM freeze on arm64 with GICv4,
where stopping a consumer is implemented by suspending the VM.
Should the connect fail, the VM will not be resumed, which
is a bit of a problem.

It also erroneously calls the producer destructor unconditionally,
which is unexpected.

Reported-by: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
Suggested-by: Marc Zyngier <maz@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Tested-by: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
[maz: tags and cc-stable, commit message update]
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Fixes: a979a6aa009f ("irqbypass: do not start cons/prod when failed connect")
Link: https://lore.kernel.org/r/3a2c66d6-6ca0-8478-d24b-61e8e3241b20@xxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210508071152.722425-1-lingshan.zhu@xxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 virt/lib/irqbypass.c |   16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

--- a/virt/lib/irqbypass.c
+++ b/virt/lib/irqbypass.c
@@ -40,21 +40,17 @@ static int __connect(struct irq_bypass_p
 	if (prod->add_consumer)
 		ret = prod->add_consumer(prod, cons);
 
-	if (ret)
-		goto err_add_consumer;
-
-	ret = cons->add_producer(cons, prod);
-	if (ret)
-		goto err_add_producer;
+	if (!ret) {
+		ret = cons->add_producer(cons, prod);
+		if (ret && prod->del_consumer)
+			prod->del_consumer(prod, cons);
+	}
 
 	if (cons->start)
 		cons->start(cons);
 	if (prod->start)
 		prod->start(prod);
-err_add_producer:
-	if (prod->del_consumer)
-		prod->del_consumer(prod, cons);
-err_add_consumer:
+
 	return ret;
 }