Re: [Xen-devel] [PATCH 2/2] 4.1.2 blktap2 cleanup fixes.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-12-12 at 17:46 +0000, Ian Jackson wrote:
> Dr. Greg Wettstein writes ("[PATCH 2/2] 4.1.2 blktap2 cleanup fixes."):
> > ---------------------------------------------------------------------------
> > The following patch when applied on top of:
> > 
> > libxl: attempt to cleanup tapdisk processes on disk backend destroy.
> > 
> > Establishes correct cleanup behavior for blktap devices.  This patch
> > implements the release of the backend device before calling for
> > the destruction of the userspace component of the blktap device.
> > 
> > Without this patch the kernel xen-blkback driver deadlocks with
> > the blktap2 user control plane until the IPC channel is terminated by the
> > timeout on the select() call.  This results in a noticeable delay
> > in the termination of the guest and causes the blktap minor
> > number which had been allocated to be orphaned.
> 
> This looks plausible.  But shouldn't it be applied to xen-unstable and
> Xen 4.2 too ?

Xen unstable and 4.2 changed in other ways which included fixing this
issue as a side effect. I can't remember which change it was but I think
it was either your asyncing up of the interfaces or the block script
stuff which I did. You can probably find out which by looking at
previous postings of this series.

So this is a fix for the code as it was in 4.1.x

Ian.



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