Re: [Xen-devel] [PATCH 2/2] libxl/devd: prevent adding spurious domains to the list

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Wed, May 10, 2017 at 05:29:12PM +0100, Wei Liu wrote:
> On Wed, May 10, 2017 at 11:12:39AM +0100, Roger Pau Monne wrote:
> > Current code in backend_watch_callback forgets to remove a 
> > libxl__ddomain_guest
> > from the list of tracked domains when the related data is freed, causing
> > dereferences later on when the list is traversed. Make sure that a domain is
> > always removed from the list when freed.
> 
> There is another bug: dguest was freed by a spurious event. That is also
> fixed by this patch.
> 
> I would suggest changing the tite to "correctly manipulate the dguest
> list" and also extend the commit message to include that other bug.

What about the following commit message:

libxl/devd: correctly manipulate the dguest list

Current code in backend_watch_callback has two issues when manipulating the
dgest list:

1. backend_watch_callback forgets to remove a libxl__ddomain_guest from the
list of tracked domains when the related data is freed, causing dereferences
later on when the list is traversed. Make sure that a domain is always removed
from the list when freed.

2. A spurious device state change can cause a dguest to be freed, with active
devices and without being removed from the list. Fix this by always checking if
a dguest has active devices before freeing and removing it.

Let me know if you want me to resend the patch or if you will fix the message
while committing.

> Code-wise:
> 
> Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Thanks.

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