On 22/01/15 03:18, Andy Lutomirski wrote:
>> --- a/drivers/xen/events/events_base.c
>> +++ b/drivers/xen/events/events_base.c
>> @@ -32,6 +32,8 @@
>> #include <linux/slab.h>
>> #include <linux/irqnr.h>
>> #include <linux/pci.h>
>> +#include <linux/sched.h>
>> +#include <linux/kprobes.h>
>>
>> #ifdef CONFIG_X86
>> #include <asm/desc.h>
>> @@ -1243,6 +1245,17 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
>> set_irq_regs(old_regs);
>> }
>>
>> +notrace void xen_end_upcall(struct pt_regs *regs)
>> +{
>> + if (!xen_is_preemptible_hypercall(regs) ||
>> + __this_cpu_read(xed_nesting_count))
>> + return;
>
> What's xed_nesting_count?
It used to prevent nested upcalls when a hypercall called from an upcall
triggers another upcall.
There's no way a such a nested hypercall can be preemptible so the check
cfor xed_nesting_count an be removed from here.
David
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