tree 38fcf034dcaba3286bd00fe9ac662876cf7aa893
parent ac80c770032c04d37d3f3f74249df66c7329cf38
author David Vrabel <david.vrabel@citrix.com> 1407427566 +0100
committer David Vrabel <david.vrabel@citrix.com> 1407754774 +0100

x86/xen: resume timer irqs early

If the timer irqs are resumed during device resume it is possible in
certain circumstances for the resume to hang early on, before device
interrupts are resumed.  For an Ubuntu 14.04 PVHVM guest this would
occur in ~0.5% of resume attempts.

It is not entirely clear what is occuring the point of the hang but I
think a task necessary for the resume calls schedule_timeout(),
waiting for a timer interrupt (which never arrives).  This failure may
require specific tasks to be running on the other VCPUs to trigger
(processes are not frozen during a suspend/resume if PREEMPT is
disabled).

Add IRQF_EARLY_RESUME to the timer interrupts so they are resumed in
syscore_resume().

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: stable@vger.kernel.org