[PATCH 1/2] virtio: fix memory leak on device removal

[PATCH 1/2] virtio: fix memory leak on device removal

[Michael S. Tsirkin]

Free up msi vector tables.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 193c8f0..dab3c86 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -489,12 +489,15 @@ static void vp_del_vq(struct virtqueue *vq)
 /* the config->del_vqs() implementation */
 static void vp_del_vqs(struct virtio_device *vdev)
 {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtqueue *vq, *n;
 
 	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 		vp_del_vq(vq);
 
 	vp_free_vectors(vdev);
+	kfree(vp_dev->msix_names);
+	kfree(vp_dev->msix_entries);
 }
 
 /* the config->find_vqs() implementation */
-- 
1.6.2.5

Re: [PATCH 1/2] virtio: fix memory leak on device removal

[Michael S. Tsirkin]

Free up msi vector tables.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Resending with corrected To list. Sorry about the churn.

 drivers/virtio/virtio_pci.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 193c8f0..dab3c86 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -489,12 +489,15 @@ static void vp_del_vq(struct virtqueue *vq)
 /* the config->del_vqs() implementation */
 static void vp_del_vqs(struct virtio_device *vdev)
 {
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtqueue *vq, *n;
 
 	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 		vp_del_vq(vq);
 
 	vp_free_vectors(vdev);
+	kfree(vp_dev->msix_names);
+	kfree(vp_dev->msix_entries);
 }
 
 /* the config->find_vqs() implementation */
-- 
1.6.2.5

Re: [PATCH 1/2] virtio: fix memory leak on device removal

[Rusty Russell]

On Wed, 22 Jul 2009 01:29:09 am Michael S. Tsirkin wrote:
> Free up msi vector tables.

Michael, this papers over the bug, but doesn't actually fix the problem.

The problem is that vp_free_vectors() does not do the reverse of 
vp_request_vectors.  If the author (you) can't get it right, what hope the 
rest of us?

Indeed, if you look harder, you'll see another leak caused by this problem, 
which your patch *didn't* fix.

Thanks,
Rusty.

Re: [PATCH 1/2] virtio: fix memory leak on device removal

[Michael S. Tsirkin]

On Thu, Jul 23, 2009 at 01:56:58PM +0930, Rusty Russell wrote:
> On Wed, 22 Jul 2009 01:29:09 am Michael S. Tsirkin wrote:
> > Free up msi vector tables.
> 
> Michael, this papers over the bug, but doesn't actually fix the problem.
> 
> The problem is that vp_free_vectors() does not do the reverse of 
> vp_request_vectors.  If the author (you) can't get it right, what hope the 
> rest of us?

I agree. This code belongs in free_vectors.
And might as well reset the pointers to make the reversal complete.

> Indeed, if you look harder, you'll see another leak caused by this problem, 
> which your patch *didn't* fix.

Couldn't spot it yet. I'll send out a fixed patch, see if I got
everything covered.

> Thanks,
> Rusty.
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[PATCH 2/2] virtio: fix double free_irq

[Michael S. Tsirkin]

Decrement used vectors counter when removing the vq so that
vp_free_vectors does not try to free the vector again.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_pci.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index dab3c86..9dcc368 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -466,8 +466,10 @@ static void vp_del_vq(struct virtqueue *vq)
 
 	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
 
-	if (info->vector != VIRTIO_MSI_NO_VECTOR)
+	if (info->vector != VIRTIO_MSI_NO_VECTOR) {
 		free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+		--vp_dev->msix_used_vectors;
+	}
 
 	if (vp_dev->msix_enabled) {
 		iowrite16(VIRTIO_MSI_NO_VECTOR,
-- 
1.6.2.5

Re: [PATCH 2/2] virtio: fix double free_irq

[Rusty Russell]

On Wed, 22 Jul 2009 01:29:25 am Michael S. Tsirkin wrote:
> -	if (info->vector != VIRTIO_MSI_NO_VECTOR)
> +	if (info->vector != VIRTIO_MSI_NO_VECTOR) {
>  		free_irq(vp_dev->msix_entries[info->vector].vector, vq);
> +		--vp_dev->msix_used_vectors;
> +	}
>

This only works because the only current caller of vp_del_vq is vp_del_vqs, so 
msix_used_vectors will be 0 after all the queues have been freed.

Make up your mind.  Either find_vq allocates and del_vq frees, or it's find_vqs 
and del_vqs.  I suggest the former, and setting the value VIRTIO_MSI_NO_VECTOR  
to indicate it's already freed.  I think with some cleanups, that loop in 
vp_free_vectors might go away, too.

Rusty.

Re: [PATCH 2/2] virtio: fix double free_irq

[Michael S. Tsirkin]

On Thu, Jul 23, 2009 at 02:10:31PM +0930, Rusty Russell wrote:
> On Wed, 22 Jul 2009 01:29:25 am Michael S. Tsirkin wrote:
> > -	if (info->vector != VIRTIO_MSI_NO_VECTOR)
> > +	if (info->vector != VIRTIO_MSI_NO_VECTOR) {
> >  		free_irq(vp_dev->msix_entries[info->vector].vector, vq);
> > +		--vp_dev->msix_used_vectors;
> > +	}
> >
> 
> This only works because the only current caller of vp_del_vq is vp_del_vqs,

Right

> so msix_used_vectors will be 0 after all the queues have been freed.

Not 0, actually, we have vectors for control and possibly
a shared vector for all vqs.

> Make up your mind.  Either find_vq allocates and del_vq frees, or it's find_vqs 
> and del_vqs.  I suggest the former, and setting the value VIRTIO_MSI_NO_VECTOR  
> to indicate it's already freed.  I think with some cleanups, that loop in 
> vp_free_vectors might go away, too.
> 
> Rusty.

IOW, msix_used_vectors counter will be for control and shared vector
for all vqs, excluding per-vq vectors.
Makes sense. I'll put out a patch.

-- 
MST

Re: [PATCH 2/2] virtio: fix double free_irq

[Michael S. Tsirkin]

On Thu, Jul 23, 2009 at 02:10:31PM +0930, Rusty Russell wrote:
> On Wed, 22 Jul 2009 01:29:25 am Michael S. Tsirkin wrote:
> > -	if (info->vector != VIRTIO_MSI_NO_VECTOR)
> > +	if (info->vector != VIRTIO_MSI_NO_VECTOR) {
> >  		free_irq(vp_dev->msix_entries[info->vector].vector, vq);
> > +		--vp_dev->msix_used_vectors;
> > +	}
> >
> 
> This only works because the only current caller of vp_del_vq is vp_del_vqs, so 
> msix_used_vectors will be 0 after all the queues have been freed.
> 
> Make up your mind.  Either find_vq allocates and del_vq frees, or it's find_vqs 
> and del_vqs.  I suggest the former, and setting the value VIRTIO_MSI_NO_VECTOR  
> to indicate it's already freed.

Hmm, there's nowhere to set this value: del_vq does kfree on info.
But I think I see a solution. Cleaned up patch RSN.

> I think with some cleanups, that loop in vp_free_vectors might go away, too.

Hmm, I don't see how, yet.
It's there to free the common vectors: config and shared vq vector.

> Rusty.
> 
> 
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