Re: [Xen-devel] [PATCH] xen-pt: Fix PCI devices re-attach failed

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 24 Dec 2014, Liang Li wrote:
> Use the 'xl pci-attach $DomU $BDF' command to attach more then
> one PCI devices to the guest, then detach the devices with
> 'xl pci-detach $DomU $BDF', after that, re-attach these PCI
> devices again, an error message will be reported like following:
> 
> libxl: error: libxl_qmp.c:287:qmp_handle_error_response: receive
> an error message from QMP server: Duplicate ID 'pci-pt-03_10.1'
> for device.
> 
> The count of calling xen_pt_region_add and xen_pt_region_del are
> not the same will cause the XenPCIPassthroughState and it's related
> QemuOpts object not be released properly.

Thanks for the patch!

From this description, I don't quite understand why the
memory_region_ref and memory_region_unref calls are wrong.  What do you
mean by "The count of calling xen_pt_region_add and xen_pt_region_del
are not the same"?

On unplug xen_pt_region_del does not get called?
Or the memory region argument is not exactly the same as the one
initially passed to xen_pt_region_add?


> Signed-off-by: Liang Li <liang.z.li@xxxxxxxxx>
> Reported-by: Longtao Pang <longtaox.pang@xxxxxxxxx>
> ---
>  hw/xen/xen_pt.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> index c1bf357..523b8a2 100644
> --- a/hw/xen/xen_pt.c
> +++ b/hw/xen/xen_pt.c
> @@ -588,7 +588,6 @@ static void xen_pt_region_add(MemoryListener *l, 
> MemoryRegionSection *sec)
>      XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
>                                               memory_listener);
>  
> -    memory_region_ref(sec->mr);
>      xen_pt_region_update(s, sec, true);
>  }
>  
> @@ -598,7 +597,6 @@ static void xen_pt_region_del(MemoryListener *l, 
> MemoryRegionSection *sec)
>                                               memory_listener);
>  
>      xen_pt_region_update(s, sec, false);
> -    memory_region_unref(sec->mr);
>  }
>  
>  static void xen_pt_io_region_add(MemoryListener *l, MemoryRegionSection *sec)
> @@ -606,7 +604,6 @@ static void xen_pt_io_region_add(MemoryListener *l, 
> MemoryRegionSection *sec)
>      XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
>                                               io_listener);
>  
> -    memory_region_ref(sec->mr);
>      xen_pt_region_update(s, sec, true);
>  }
>  
> @@ -616,7 +613,6 @@ static void xen_pt_io_region_del(MemoryListener *l, 
> MemoryRegionSection *sec)
>                                               io_listener);
>  
>      xen_pt_region_update(s, sec, false);
> -    memory_region_unref(sec->mr);
>  }
>  
>  static const MemoryListener xen_pt_memory_listener = {
> -- 
> 1.9.1
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel