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

[Wei Liu <wei.liu@kernel.org>]

On Thu, Aug 29, 2024 at 06:40:16AM -0700, Saurabh Singh Sengar wrote:
> 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 +	 * from vmbus when the primary channel is rescinded.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> 

Applied to hyperv-fixes, thanks.

>