Re: [Xen-devel] [PATCH for-4.13 v2] passthrough: simplify locking and logging

["Durrant, Paul" <pdurrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Sent: 04 November 2019 11:06
> To: Durrant, Paul <pdurrant@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>; jgross@xxxxxxxx;
> jbeulich@xxxxxxxx
> Subject: Re: [Xen-devel] [PATCH for-4.13 v2] passthrough: simplify locking
> and logging
> 
> On 04/11/2019 08:31, Durrant, Paul wrote:
> >> -----Original Message-----
> >> From: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
> >> Sent: 01 November 2019 19:28
> >> To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> >> Cc: Durrant, Paul <pdurrant@xxxxxxxxxx>; jbeulich@xxxxxxxx;
> >> jgross@xxxxxxxx
> >> Subject: [PATCH for-4.13 v2] passthrough: simplify locking and logging
> >>
> >> From: Paul Durrant <pdurrant@xxxxxxxxxx>
> >>
> >> Dropping the pcidevs lock between calling device_assigned() and
> >> assign_device() means that the latter has to do the same check as the
> >> former for no obvious gain. Also, since long running operations under
> >> pcidevs lock already drop the lock and return -ERESTART periodically
> there
> >> is little point in immediately failing an assignment operation with
> >> -ERESTART just because the pcidevs lock could not be acquired (for the
> >> second time, having already blocked on acquiring the lock in
> >> device_assigned()).
> >>
> >> This patch instead acquires the lock once for assignment (or test
> assign)
> >> operations directly in iommu_do_pci_domctl() and thus can remove the
> >> duplicate domain ownership check in assign_device(). Whilst in the
> >> neighbourhood, the patch also removes some debug logging from
> >> assign_device() and deassign_device() and replaces it with proper error
> >> logging, which allows error logging in iommu_do_pci_domctl() to be
> >> removed. Also, since device_assigned() can tell the difference between
> a
> >> guest assigned device and a non-existent one, log the actual error
> >> condition rather then being ambiguous for the sake a few extra lines of
> >> code.
> >>
> >> Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
> >> ---
> >>
> >> This is XSA-302 followup and contains some changes important for
> >> XenServer.
> >> Juergen, could this be considered for 4.13 inclusion?
> >>
> >> v2: updated Paul's email address
> 
> This was work you did at Citrix, yes?
> 
> > Reviewed-by: Paul Durrant <pdurrant@xxxxxxxxxx>
> 
> SoB and R-by?

I did do the work while I was at Citrix, but surely the SoB must be updated 
since the patch is only now being posted? As for the R-b, why should that be 
historic?

  Paul

> 
> ~Andrew
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