[GIT pull] irq fixes for 4.3

[Thomas Gleixner <tglx@linutronix.de>]

Linus,

please pull the latest irq-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq-urgent-for-linus

This update contains:

     - Fix for a long standing race affecting /proc/irq/NNN

     - One line fix for ARM GICV3-ITS counting the wrong data

     - Warning silencing in ARM GICV3-ITS. Another GCC trying to be
       overly clever issue.

Thanks,

	tglx

------------------>
Ben Hutchings (1):
      genirq: Fix race in register_irq_proc()

Marc Zyngier (2):
      irqchip/gic-v3-its: Silence warning when its_lpi_alloc_chunks gets inlined
      irqchip/gic-v3-its: Count additional LPIs for the aliased devices


 drivers/irqchip/irq-gic-v3-its-pci-msi.c |  2 +-
 drivers/irqchip/irq-gic-v3-its.c         |  3 +++
 kernel/irq/proc.c                        | 19 +++++++++++++++++--
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its-pci-msi.c b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
index cf351c637464..a7c8c9ffbafd 100644
--- a/drivers/irqchip/irq-gic-v3-its-pci-msi.c
+++ b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
@@ -62,7 +62,7 @@ static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
 
 	dev_alias->dev_id = alias;
 	if (pdev != dev_alias->pdev)
-		dev_alias->count += its_pci_msi_vec_count(dev_alias->pdev);
+		dev_alias->count += its_pci_msi_vec_count(pdev);
 
 	return 0;
 }
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index ac7ae2b3cb83..25ceae9f7348 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -719,6 +719,9 @@ static unsigned long *its_lpi_alloc_chunks(int nr_irqs, int *base, int *nr_ids)
 out:
 	spin_unlock(&lpi_lock);
 
+	if (!bitmap)
+		*base = *nr_ids = 0;
+
 	return bitmap;
 }
 
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index e3a8c9577ba6..a50ddc9417ff 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/mutex.h>
 
 #include "internals.h"
 
@@ -323,18 +324,29 @@ void register_handler_proc(unsigned int irq, struct irqaction *action)
 
 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
+	static DEFINE_MUTEX(register_lock);
 	char name [MAX_NAMELEN];
 
-	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip) || desc->dir)
+	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
 		return;
 
+	/*
+	 * irq directories are registered only when a handler is
+	 * added, not when the descriptor is created, so multiple
+	 * tasks might try to register at the same time.
+	 */
+	mutex_lock(&register_lock);
+
+	if (desc->dir)
+		goto out_unlock;
+
 	memset(name, 0, MAX_NAMELEN);
 	sprintf(name, "%d", irq);
 
 	/* create /proc/irq/1234 */
 	desc->dir = proc_mkdir(name, root_irq_dir);
 	if (!desc->dir)
-		return;
+		goto out_unlock;
 
 #ifdef CONFIG_SMP
 	/* create /proc/irq/<irq>/smp_affinity */
@@ -355,6 +367,9 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 
 	proc_create_data("spurious", 0444, desc->dir,
 			 &irq_spurious_proc_fops, (void *)(long)irq);
+
+out_unlock:
+	mutex_unlock(&register_lock);
 }
 
 void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)