hw/virtio/vdpa-dev.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
As the comment in qapi/error, dereferencing @errp requires
ERRP_GUARD():
* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
* - It must not be dereferenced, because it may be null.
...
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.
*
* Using it when it's not needed is safe, but please avoid cluttering
* the source with useless code.
Though vhost_vdpa_device_realize() is called at DeviceClass.realize()
context and won't get NULL @errp, it's still better to follow the
requirement to add the ERRP_GUARD().
But qemu_open() and vhost_vdpa_device_get_u32()'s return values can
distinguish between successful and unsuccessful calls, so check the
return values directly without dereferencing @errp, which eliminates
the need of ERRP_GUARD().
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Eugenio Pérez" <eperezma@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
hw/virtio/vdpa-dev.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
index 64b96b226c39..7b439efdc1d3 100644
--- a/hw/virtio/vdpa-dev.c
+++ b/hw/virtio/vdpa-dev.c
@@ -50,6 +50,7 @@ vhost_vdpa_device_get_u32(int fd, unsigned long int cmd, Error **errp)
static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
{
+ ERRP_GUARD();
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VhostVdpaDevice *v = VHOST_VDPA_DEVICE(vdev);
struct vhost_vdpa_iova_range iova_range;
@@ -63,19 +64,19 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
}
v->vhostfd = qemu_open(v->vhostdev, O_RDWR, errp);
- if (*errp) {
+ if (v->vhostfd < 0) {
return;
}
v->vdev_id = vhost_vdpa_device_get_u32(v->vhostfd,
VHOST_VDPA_GET_DEVICE_ID, errp);
- if (*errp) {
+ if (v->vdev_id < 0) {
goto out;
}
max_queue_size = vhost_vdpa_device_get_u32(v->vhostfd,
VHOST_VDPA_GET_VRING_NUM, errp);
- if (*errp) {
+ if (max_queue_size < 0) {
goto out;
}
@@ -89,7 +90,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
v->num_queues = vhost_vdpa_device_get_u32(v->vhostfd,
VHOST_VDPA_GET_VQS_COUNT, errp);
- if (*errp) {
+ if (v->num_queues < 0) {
goto out;
}
@@ -127,7 +128,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
v->config_size = vhost_vdpa_device_get_u32(v->vhostfd,
VHOST_VDPA_GET_CONFIG_SIZE,
errp);
- if (*errp) {
+ if (v->config_size < 0) {
goto vhost_cleanup;
}
--
2.34.1
On Mon, Jul 15, 2024 at 11:45 AM Zhao Liu <zhao1.liu@intel.com> wrote:
>
> As the comment in qapi/error, dereferencing @errp requires
> ERRP_GUARD():
>
> * = Why, when and how to use ERRP_GUARD() =
> *
> * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> * - It must not be dereferenced, because it may be null.
> ...
> * ERRP_GUARD() lifts these restrictions.
> *
> * To use ERRP_GUARD(), add it right at the beginning of the function.
> * @errp can then be used without worrying about the argument being
> * NULL or &error_fatal.
> *
> * Using it when it's not needed is safe, but please avoid cluttering
> * the source with useless code.
>
> Though vhost_vdpa_device_realize() is called at DeviceClass.realize()
> context and won't get NULL @errp, it's still better to follow the
> requirement to add the ERRP_GUARD().
>
> But qemu_open() and vhost_vdpa_device_get_u32()'s return values can
> distinguish between successful and unsuccessful calls, so check the
> return values directly without dereferencing @errp, which eliminates
> the need of ERRP_GUARD().
>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: "Eugenio Pérez" <eperezma@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> hw/virtio/vdpa-dev.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
> index 64b96b226c39..7b439efdc1d3 100644
> --- a/hw/virtio/vdpa-dev.c
> +++ b/hw/virtio/vdpa-dev.c
> @@ -50,6 +50,7 @@ vhost_vdpa_device_get_u32(int fd, unsigned long int cmd, Error **errp)
>
> static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> {
> + ERRP_GUARD();
Good catch, thank you! But removing the err dereferencing eliminates
the need for ERRP_GUARD(), doesn't it?
Thanks!
> VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> VhostVdpaDevice *v = VHOST_VDPA_DEVICE(vdev);
> struct vhost_vdpa_iova_range iova_range;
> @@ -63,19 +64,19 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> }
>
> v->vhostfd = qemu_open(v->vhostdev, O_RDWR, errp);
> - if (*errp) {
> + if (v->vhostfd < 0) {
> return;
> }
>
> v->vdev_id = vhost_vdpa_device_get_u32(v->vhostfd,
> VHOST_VDPA_GET_DEVICE_ID, errp);
> - if (*errp) {
> + if (v->vdev_id < 0) {
> goto out;
> }
>
> max_queue_size = vhost_vdpa_device_get_u32(v->vhostfd,
> VHOST_VDPA_GET_VRING_NUM, errp);
> - if (*errp) {
> + if (max_queue_size < 0) {
> goto out;
> }
>
> @@ -89,7 +90,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
>
> v->num_queues = vhost_vdpa_device_get_u32(v->vhostfd,
> VHOST_VDPA_GET_VQS_COUNT, errp);
> - if (*errp) {
> + if (v->num_queues < 0) {
> goto out;
> }
>
> @@ -127,7 +128,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> v->config_size = vhost_vdpa_device_get_u32(v->vhostfd,
> VHOST_VDPA_GET_CONFIG_SIZE,
> errp);
> - if (*errp) {
> + if (v->config_size < 0) {
> goto vhost_cleanup;
> }
>
> --
> 2.34.1
>
On Mon, Jul 15, 2024 at 11:01:08PM +0200, Eugenio Perez Martin wrote:
> Date: Mon, 15 Jul 2024 23:01:08 +0200
> From: Eugenio Perez Martin <eperezma@redhat.com>
> Subject: Re: [PATCH] hw/virtio/vdpa-dev: Check returned value instead of
> dereferencing @errp
>
> On Mon, Jul 15, 2024 at 11:45 AM Zhao Liu <zhao1.liu@intel.com> wrote:
> >
> > As the comment in qapi/error, dereferencing @errp requires
> > ERRP_GUARD():
> >
> > * = Why, when and how to use ERRP_GUARD() =
> > *
> > * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> > * - It must not be dereferenced, because it may be null.
> > ...
> > * ERRP_GUARD() lifts these restrictions.
> > *
> > * To use ERRP_GUARD(), add it right at the beginning of the function.
> > * @errp can then be used without worrying about the argument being
> > * NULL or &error_fatal.
> > *
> > * Using it when it's not needed is safe, but please avoid cluttering
> > * the source with useless code.
> >
> > Though vhost_vdpa_device_realize() is called at DeviceClass.realize()
> > context and won't get NULL @errp, it's still better to follow the
> > requirement to add the ERRP_GUARD().
> >
> > But qemu_open() and vhost_vdpa_device_get_u32()'s return values can
> > distinguish between successful and unsuccessful calls, so check the
> > return values directly without dereferencing @errp, which eliminates
> > the need of ERRP_GUARD().
> >
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: "Eugenio Pérez" <eperezma@redhat.com>
> > Cc: Jason Wang <jasowang@redhat.com>
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> > ---
> > hw/virtio/vdpa-dev.c | 11 ++++++-----
> > 1 file changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
> > index 64b96b226c39..7b439efdc1d3 100644
> > --- a/hw/virtio/vdpa-dev.c
> > +++ b/hw/virtio/vdpa-dev.c
> > @@ -50,6 +50,7 @@ vhost_vdpa_device_get_u32(int fd, unsigned long int cmd, Error **errp)
> >
> > static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> > {
> > + ERRP_GUARD();
>
> Good catch, thank you! But removing the err dereferencing eliminates
> the need for ERRP_GUARD(), doesn't it?
>
Thanks Eugenio! You're right and I forgot to delete it. I'll post a new
version.
On Tue, Jul 16, 2024 at 5:05 AM Zhao Liu <zhao1.liu@intel.com> wrote:
>
> On Mon, Jul 15, 2024 at 11:01:08PM +0200, Eugenio Perez Martin wrote:
> > Date: Mon, 15 Jul 2024 23:01:08 +0200
> > From: Eugenio Perez Martin <eperezma@redhat.com>
> > Subject: Re: [PATCH] hw/virtio/vdpa-dev: Check returned value instead of
> > dereferencing @errp
> >
> > On Mon, Jul 15, 2024 at 11:45 AM Zhao Liu <zhao1.liu@intel.com> wrote:
> > >
> > > As the comment in qapi/error, dereferencing @errp requires
> > > ERRP_GUARD():
> > >
> > > * = Why, when and how to use ERRP_GUARD() =
> > > *
> > > * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> > > * - It must not be dereferenced, because it may be null.
> > > ...
> > > * ERRP_GUARD() lifts these restrictions.
> > > *
> > > * To use ERRP_GUARD(), add it right at the beginning of the function.
> > > * @errp can then be used without worrying about the argument being
> > > * NULL or &error_fatal.
> > > *
> > > * Using it when it's not needed is safe, but please avoid cluttering
> > > * the source with useless code.
> > >
> > > Though vhost_vdpa_device_realize() is called at DeviceClass.realize()
> > > context and won't get NULL @errp, it's still better to follow the
> > > requirement to add the ERRP_GUARD().
> > >
> > > But qemu_open() and vhost_vdpa_device_get_u32()'s return values can
> > > distinguish between successful and unsuccessful calls, so check the
> > > return values directly without dereferencing @errp, which eliminates
> > > the need of ERRP_GUARD().
> > >
> > > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > > Cc: "Eugenio Pérez" <eperezma@redhat.com>
> > > Cc: Jason Wang <jasowang@redhat.com>
> > > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> > > ---
> > > hw/virtio/vdpa-dev.c | 11 ++++++-----
> > > 1 file changed, 6 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
> > > index 64b96b226c39..7b439efdc1d3 100644
> > > --- a/hw/virtio/vdpa-dev.c
> > > +++ b/hw/virtio/vdpa-dev.c
> > > @@ -50,6 +50,7 @@ vhost_vdpa_device_get_u32(int fd, unsigned long int cmd, Error **errp)
> > >
> > > static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> > > {
> > > + ERRP_GUARD();
> >
> > Good catch, thank you! But removing the err dereferencing eliminates
> > the need for ERRP_GUARD(), doesn't it?
> >
>
> Thanks Eugenio! You're right and I forgot to delete it. I'll post a new
> version.
>
>
Good! With that removed,
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Thanks!
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