lguest: Make sure interrupt is allocated ok by lguest_setup_irq

Make sure the interrupt is allocated correctly by lguest_setup_irq (check the
return value of irq_alloc_desc_at for -ENOMEM)

Signed-off-by: Stratos Psomadakis <psomas@cslab.ece.ntua.gr>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cleanups and commentry)

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 6a1d6447b864..9e8388efd88e 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -241,7 +241,7 @@ static void lg_notify(struct virtqueue *vq)
 }
 
 /* An extern declaration inside a C file is bad form.  Don't do it. */
-extern void lguest_setup_irq(unsigned int irq);
+extern int lguest_setup_irq(unsigned int irq);
 
 /*
  * This routine finds the Nth virtqueue described in the configuration of
@@ -304,7 +304,9 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
         }
 
         /* Make sure the interrupt is allocated. */
-        lguest_setup_irq(lvq->config.irq);
+        err = lguest_setup_irq(lvq->config.irq);
+        if (err)
+                goto destroy_vring;
 
         /*
          * Tell the interrupt for this virtqueue to go to the virtio_ring
@@ -317,7 +319,7 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
         err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
                           dev_name(&vdev->dev), vq);
         if (err)
-                goto destroy_vring;
+                goto free_desc;
 
         /*
          * Last of all we hook up our 'struct lguest_vq_info" to the
@@ -326,6 +328,8 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
         vq->priv = lvq;
         return vq;
 
+free_desc:
+        irq_free_desc(lvq->config.irq);
 destroy_vring:
         vring_del_virtqueue(vq);
 unmap: