| Message ID | 20240716162615.271010-1-zhao1.liu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] hw/virtio/vdpa-dev: Check returned value instead of dereferencing @errp | expand |
On Wed, Jul 17, 2024 at 12:26:15AM +0800, Zhao Liu 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: Jason Wang <jasowang@redhat.com> > Acked-by: Eugenio Pérez <eperezma@redhat.com> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com> > --- > v2: > * Added a/b from Eugenio. > * Deleted unnecessary ERRP_GUARD(). (Eugenio) > --- > hw/virtio/vdpa-dev.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c > index 64b96b226c39..8a1e16fce3de 100644 > --- a/hw/virtio/vdpa-dev.c > +++ b/hw/virtio/vdpa-dev.c > @@ -63,19 +63,19 @@ 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; > } vdev_id is unsigned, no idea how is this supposed to work. > > 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; > } > max_queue_size is unsigned, too. > @@ -89,7 +89,7 @@ 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; > } > num_queues is unsigned, too. > @@ -127,7 +127,7 @@ 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
Hi Michael, On Tue, Aug 20, 2024 at 06:55:29AM -0400, Michael S. Tsirkin wrote: [snip] > > diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c > > index 64b96b226c39..8a1e16fce3de 100644 > > --- a/hw/virtio/vdpa-dev.c > > +++ b/hw/virtio/vdpa-dev.c > > @@ -63,19 +63,19 @@ 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; > > } > > vdev_id is unsigned, no idea how is this supposed to work. > > > > > 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; > > } > > > max_queue_size is unsigned, too. > > > @@ -89,7 +89,7 @@ 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; > > } > > > > num_queues is unsigned, too. Oops, yes. The correct way is to check whether vhost_vdpa_device_get_u32 returns "(uint32_t)-1". I can add a new macro like this: #define VDPA_DEVICE_U32_VALUE_NONE ((uint32_t)-1) Is this okay with you? Thanks, Zhao > > @@ -127,7 +127,7 @@ 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 >
diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c index 64b96b226c39..8a1e16fce3de 100644 --- a/hw/virtio/vdpa-dev.c +++ b/hw/virtio/vdpa-dev.c @@ -63,19 +63,19 @@ 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 +89,7 @@ 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 +127,7 @@ 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; }