[Qemu-devel] [PULL 21/40] ivshmem: Assert interrupts are set up once

[Markus Armbruster <armbru@redhat.com>]

An interrupt is set up when the interrupt's file descriptor is
received.  Each message applies to the next interrupt vector.
Therefore, each vector cannot be set up more than once.

ivshmem_add_kvm_msi_virq() half-heartedly tries not to rely on this by
doing nothing then, but that's not going to recover from this error
should it become possible in the future.  watch_vector_notifier()
doesn't even try.

Simply assert what is the case, so we get alerted if we ever screw it
up.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-22-git-send-email-armbru@redhat.com>
---
 hw/misc/ivshmem.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 65e3a76..61e21cd 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -349,7 +349,7 @@ static void watch_vector_notifier(IVShmemState *s, EventNotifier *n,
 {
     int eventfd = event_notifier_get_fd(n);
 
-    /* if MSI is supported we need multiple interrupts */
+    assert(!s->msi_vectors[vector].pdev);
     s->msi_vectors[vector].pdev = PCI_DEVICE(s);
 
     qemu_set_fd_handler(eventfd, ivshmem_vector_notify,
@@ -535,10 +535,7 @@ static int ivshmem_add_kvm_msi_virq(IVShmemState *s, int vector)
     int ret;
 
     IVSHMEM_DPRINTF("ivshmem_add_kvm_msi_virq vector:%d\n", vector);
-
-    if (s->msi_vectors[vector].pdev != NULL) {
-        return 0;
-    }
+    assert(!s->msi_vectors[vector].pdev);
 
     ret = kvm_irqchip_add_msi_route(kvm_state, msg, pdev);
     if (ret < 0) {
-- 
2.4.3