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Subject[PATCH 4/5] xen/spinlock: Don't setup xen spinlock IPI kicker if disabled.
Date
There is no need to setup this kicker IPI if we are never going
to use the paravirtualized ticketlock mechanism.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
---
arch/x86/xen/spinlock.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 71db82c..e1bff87 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -105,6 +105,7 @@ static DEFINE_PER_CPU(char *, irq_name);
static DEFINE_PER_CPU(struct xen_lock_waiting, lock_waiting);
static cpumask_t waiting_cpus;

+static bool xen_pvspin __initdata = true;
static void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
{
int irq = __this_cpu_read(lock_kicker_irq);
@@ -223,6 +224,9 @@ void xen_init_lock_cpu(int cpu)
int irq;
char *name;

+ if (!xen_pvspin)
+ return;
+
WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
cpu, per_cpu(lock_kicker_irq, cpu));

@@ -259,13 +263,15 @@ void xen_uninit_lock_cpu(int cpu)
if (xen_hvm_domain())
return;

+ if (!xen_pvspin)
+ return;
+
unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
per_cpu(lock_kicker_irq, cpu) = -1;
kfree(per_cpu(irq_name, cpu));
per_cpu(irq_name, cpu) = NULL;
}

-static bool xen_pvspin __initdata = true;

void __init xen_init_spinlocks(void)
{
@@ -305,6 +311,9 @@ static int __init xen_spinlock_debugfs(void)
if (d_xen == NULL)
return -ENOMEM;

+ if (!xen_pvspin)
+ return 0;
+
d_spin_debug = debugfs_create_dir("spinlocks", d_xen);

debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
--
1.8.3.1


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