> From: Zhu, Lingshan <lingshan.zhu@xxxxxxxxx>
> Sent: Tuesday, July 26, 2022 7:03 AM
>
> On 7/24/2022 11:21 PM, Parav Pandit wrote:
> >
> >> From: Zhu, Lingshan <lingshan.zhu@xxxxxxxxx>
> >> Sent: Saturday, July 23, 2022 7:24 AM
> >>
> >>
> >> On 7/22/2022 9:12 PM, Parav Pandit wrote:
> >>>> From: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> >>>> Sent: Friday, July 22, 2022 7:53 AM
> >>>>
> >>>> This commit adds a new vDPA netlink attribution
> >>>> VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES. Userspace can
> query
> >> features
> >>>> of vDPA devices through this new attr.
> >>>>
> >>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> >>>> ---
> >>>> drivers/vdpa/vdpa.c | 13 +++++++++----
> >>>> include/uapi/linux/vdpa.h | 1 +
> >>>> 2 files changed, 10 insertions(+), 4 deletions(-)
> >>>>
> >>>> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index
> >>>> ebf2f363fbe7..9b0e39b2f022 100644
> >>>> --- a/drivers/vdpa/vdpa.c
> >>>> +++ b/drivers/vdpa/vdpa.c
> >>>> @@ -815,7 +815,7 @@ static int vdpa_dev_net_mq_config_fill(struct
> >>>> vdpa_device *vdev, static int vdpa_dev_net_config_fill(struct
> >>>> vdpa_device *vdev, struct sk_buff *msg) {
> >>>> struct virtio_net_config config = {};
> >>>> - u64 features;
> >>>> + u64 features_device, features_driver;
> >>>> u16 val_u16;
> >>>>
> >>>> vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config)); @@
> >>>> -
> >>>> 832,12 +832,17 @@ static int vdpa_dev_net_config_fill(struct
> >>>> vdpa_device *vdev, struct sk_buff *ms
> >>>> if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
> >>>> return -EMSGSIZE;
> >>>>
> >>>> - features = vdev->config->get_driver_features(vdev);
> >>>> - if (nla_put_u64_64bit(msg,
> >>>> VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features,
> >>>> + features_driver = vdev->config->get_driver_features(vdev);
> >>>> + if (nla_put_u64_64bit(msg,
> >>>> VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
> >>>> + VDPA_ATTR_PAD))
> >>>> + return -EMSGSIZE;
> >>>> +
> >>>> + features_device = vdev->config->get_device_features(vdev);
> >>>> + if (nla_put_u64_64bit(msg,
> >>>> VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,
> >>>> +features_device,
> >>>> VDPA_ATTR_PAD))
> >>>> return -EMSGSIZE;
> >>>>
> >>>> - return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> >>>> + return vdpa_dev_net_mq_config_fill(vdev, msg, features_driver,
> >>>> +&config);
> >>>> }
> >>>>
> >>>> static int
> >>>> diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> >>>> index
> >>>> 25c55cab3d7c..39f1c3d7c112 100644
> >>>> --- a/include/uapi/linux/vdpa.h
> >>>> +++ b/include/uapi/linux/vdpa.h
> >>>> @@ -47,6 +47,7 @@ enum vdpa_attr {
> >>>> VDPA_ATTR_DEV_NEGOTIATED_FEATURES, /* u64 */
> >>>> VDPA_ATTR_DEV_MGMTDEV_MAX_VQS, /* u32 */
> >>>> VDPA_ATTR_DEV_SUPPORTED_FEATURES, /* u64 */
> >>>> + VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, /* u64 */
> >>>>
> >>> I have answered in previous emails.
> >>> I disagree with the change.
> >>> Please reuse VDPA_ATTR_DEV_SUPPORTED_FEATURES.
> >> I believe we have already discussed this before in the V3 thread.
> >> I have told you that reusing this attr will lead to a new race condition.
> >>
> > Returning attribute cannot lead to any race condition.
> Please refer to our discussion in the V3 series, I have explained if re-use this
> attr, it will be a multiple consumers and multiple produces model, it is a
> typical racing condition.
I read the emails with subject = " Re: [PATCH V3 3/6] vDPA: allow userspace to query features of a vDPA device"
I couldn’t find multiple consumers multiple producers working on same nla message.
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