Re: [PATCH v2 2/2] Drivers: hv: vmbus: Fix rescind handling in uio_hv_generic

Saurabh Singh Sengar
2024-08-29T13:40:17Z

On Thu, Aug 29, 2024 at 12:43:12PM +0530, Naman Jain wrote:
> Rescind offer handling relies on rescind callbacks for some of the
> resources cleanup, if they are registered. It does not unregister
> vmbus device for the primary channel closure, when callback is
> registered. Without it, next onoffer does not come, rescind flag
> remains set and device goes to unusable state.
>
> Add logic to unregister vmbus for the primary channel in rescind callback
> to ensure channel removal and relid release, and to ensure that next
> onoffer can be received and handled properly.
>
> Cc: stable@vger.kernel.org
> Fixes: ca3cda6fcf1e ("uio_hv_generic: add rescind support")
> Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
> ---
> drivers/hv/vmbus_drv.c | 1 +
> drivers/uio/uio_hv_generic.c | 8 ++++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 7242c4920427..c405295b930a 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1980,6 +1980,7 @@ void vmbus_device_unregister(struct hv_device *device_obj)
> */
> device_unregister(&device_obj->device);
> }
> +EXPORT_SYMBOL_GPL(vmbus_device_unregister);
>
> #ifdef CONFIG_ACPI
> /*
> diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
> index e3e66a3e85a8..870409599411 100644
> --- a/drivers/uio/uio_hv_generic.c
> +++ b/drivers/uio/uio_hv_generic.c
> @@ -121,6 +121,14 @@ static void hv_uio_rescind(struct vmbus_channel *channel)
>
> /* Wake up reader */
> uio_event_notify(&pdata->info);
> +
> + /*
> + * With rescind callback registered, rescind path will not unregister the device
> + * from vmbus when the primary channel is rescinded.
> + * Without it, rescind handling is incomplete and next onoffer msg does not come.
> + * Unregister the device from vmbus here.
> + */
> + vmbus_device_unregister(channel->device_obj);
> }
>
> /* Sysfs API to allow mmap of the ring buffers
> --
> 2.34.1
>

For the series,
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>