Re: [Xen-devel] request for the hotplug scripts

[Stefan Berger <stefanb@xxxxxxxxxx>]

Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote
on 11/21/2005 04:56:15 AM:

> 
> On 20 Nov 2005, at 23:42, Stefan Berger wrote:
> 
> >
> > Hello!
> >
> >   I have a question for the hotplug scripts that are used
for the 
> > network, block and soon the TPM interface. Would it be possible
if an 
> > environment variable 'REASON' was set that reflects whether a
domain 
> > was 'creat'ed or 'resume'd after a suspend. This can be very
helpful 
> > in initializing devices differently depending on the 'reason',
such as 
> > a 'reset' if it is 'created' and not doing a 'reset' if it was
> > resumed. I would try to add this 'REASON' variable myself - but
where 
> > for example is the 'ACTION' being set? I see XENBUS_PATH and
> > XENBUS_TYPE stem from xenbus_probe.c, but I could not find the
origin 
> > of the 'ACTION' variable.
> 
> ACTION is a standard hotplug env var, set up by the generic hotplug
> subsystem. You would add a new var such as REASON in the same place
> that XENBUS_TYPE/PATH are set.

I added the REASON parameter to the function where
the XENBUS_TYPE/PATH are set. It only differentiates between 'hibernation'
(=suspend/resume) and 'creation' (create/destroy). However, this makes
the REASON only correctly visible to the user domain and not domain 0 where
I need to know about it. Could it be that the backend side of the driver
as well as the xenbus on the backend side do not know that the corresponding
frontend is changing state due to a suspend vs. a destroy?

experimental patch below.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxx>

-- Stefan


Index: root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
@@ -247,6 +247,11 @@ static int xenbus_hotplug_backend(struct
         
               
   buffer, buffer_size, &length,
         
               
   "XENBUS_PATH=%s", xdev->nodename);
 
+        add_hotplug_env_var(envp,
num_envp, &i,
+          
                 buffer, buffer_size,
&length,
+          
                 "REASON=%s",
xdev->is_hibernating ? "hibernation"
+          
                     
                     
       : "creation");
+        xdev->is_hibernating
= 0;
         /*
terminate, set to next free slot, shrink available space */
         envp[i]
= NULL;
         envp
= &envp[i];
@@ -789,8 +794,10 @@ static int suspend_dev(struct
device *de
         
       return 0;
         drv
= to_xenbus_driver(dev->driver);
         xdev
= container_of(dev, struct xenbus_device, dev);
-        if
(drv->suspend)
+        xdev->is_hibernating
= 1;
+        if
(drv->suspend) {
         
       err = drv->suspend(xdev);
+        }
         if
(err)
         
       printk(KERN_WARNING
         
              "xenbus:
suspend %s failed: %i\n", dev->bus_id, err);
@@ -818,8 +825,10 @@ static int resume_dev(struct
device *dev
         
       return err;
         }
 
-        if
(drv->resume)
+        xdev->is_hibernating
= 1;
+        if
(drv->resume) {
         
       err = drv->resume(xdev);
+        }
         if
(err)
         
       printk(KERN_WARNING
         
              "xenbus:
resume %s failed: %i\n", dev->bus_id, err);
Index: root/xen-unstable.hg/linux-2.6-xen-sparse/include/asm-xen/xenbus.h
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/include/asm-xen/xenbus.h
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/include/asm-xen/xenbus.h
@@ -79,6 +79,7 @@ struct xenbus_device
{
         struct
xenbus_watch otherend_watch;
         struct
device dev;
         int
has_error;
+        int
is_hibernating;
         void
*data;
 };
 

> 
>   -- Keir
> 
> 
> > Cheers!
> >  Stefan
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
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