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xen: yield to IPI target if necessary

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When sending a call-function IPI to a vcpu, yield if the vcpu isn't
running.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
This commit is contained in:
Jeremy Fitzhardinge
2007-10-16 11:51:30 -07:00
committed by Jeremy Fitzhardinge
parent d626a1f1cb
commit f0d7339427
3 changed files with 18 additions and 4 deletions
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14
arch/x86/xen/smp.c
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@@ -360,7 +360,8 @@ int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
void *info, int wait)
{
struct call_data_struct data;
int cpus;
int cpus, cpu;
bool yield;
/* Holding any lock stops cpus from going down. */
spin_lock(&call_lock);
@@ -389,9 +390,14 @@ int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
/* Send a message to other CPUs and wait for them to respond */
xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
/* Make sure other vcpus get a chance to run.
XXX too severe? Maybe we should check the other CPU's states? */
HYPERVISOR_sched_op(SCHEDOP_yield, 0);
/* Make sure other vcpus get a chance to run if they need to. */
yield = false;
for_each_cpu_mask(cpu, mask)
if (xen_vcpu_stolen(cpu))
yield = true;
if (yield)
HYPERVISOR_sched_op(SCHEDOP_yield, 0);
/* Wait for response */
while (atomic_read(&data.started) != cpus ||