On 07/14/2015 11:44 AM, Thomas Gleixner wrote:
On Tue, 14 Jul 2015, Boris Ostrovsky wrote:
Prevent allocation and freeing of interrupt descriptors accross cpu
hotplug.
This breaks Xen guests that allocate interrupt descriptors in .cpu_up().
And where exactly does XEN allocate those descriptors?
xen_cpu_up()
xen_setup_timer()
bind_virq_to_irqhandler()
bind_virq_to_irq()
xen_allocate_irq_dynamic()
xen_allocate_irqs_dynamic()
irq_alloc_descs()
There is also a similar pass via xen_cpu_up() -> xen_smp_intr_init()
Any chance this locking can be moved into arch code?
No.
(The patch doesn't appear to have any side effects for the down path since Xen
guests deallocate descriptors in __cpu_die()).
Exact place please.
Whose place? Where descriptors are deallocated?
__cpu_die()
xen_cpu_die()
xen_teardown_timer()
unbind_from_irqhandler()
unbind_from_irq()
__unbind_from_irq()
xen_free_irq()
irq_free_descs()
free_desc()
-boris
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