linux-kernel - [PATCH 4/5] xen/spinlock: Don't setup xen spinlock IPI kicker if disabled.

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Date:	Mon,  9 Sep 2013 11:11:35 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
	boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
	stefan.bader@...onical.com, stefano.stabellini@...citrix.com,
	jeremy@...p.org
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 4/5] xen/spinlock: Don't setup xen spinlock IPI kicker if disabled.

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@...cle.com>
Reviewed-by: David Vrabel <david.vrabel@...rix.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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