[Xen-devel] [PATCH] xen/arm: Implement dynamic allocation of irq descriptors

[vijay.kilari@xxxxxxxxx]

From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>

For arm memory for 1024 irq descriptors are allocated
statically irrespective of number of interrupt supported
by the platform.

With this patch, irq descriptors are allocated at run time
and managed using red-black tree. Functions to insert, search
and delete irq descriptor are implemented in xen/common/irq.c.

Signed-off-by: Vijaya Kumar K<Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
---
 xen/arch/arm/irq.c    |   83 +++++++++++++++++++++++++++++++++++++++----------
 xen/common/irq.c      |   58 ++++++++++++++++++++++++++++++++++
 xen/include/xen/irq.h |    6 ++++
 3 files changed, 130 insertions(+), 17 deletions(-)

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index cb9c99b..856aecf 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -30,6 +30,7 @@
 
 static unsigned int local_irqs_type[NR_LOCAL_IRQS];
 static DEFINE_SPINLOCK(local_irqs_type_lock);
+static DEFINE_SPINLOCK(rb_tree_desc_lock);
 
 static void ack_none(struct irq_desc *irq)
 {
@@ -48,33 +49,35 @@ hw_irq_controller no_irq_type = {
     .end = end_none
 };
 
-static irq_desc_t irq_desc[NR_IRQS];
+static struct rb_root desc_root;
+
 static DEFINE_PER_CPU(irq_desc_t[NR_LOCAL_IRQS], local_irq_desc);
 
 irq_desc_t *__irq_to_desc(int irq)
 {
+    struct irq_desc *desc;
+
     if (irq < NR_LOCAL_IRQS) return &this_cpu(local_irq_desc)[irq];
-    return &irq_desc[irq-NR_LOCAL_IRQS];
+
+    spin_lock(&rb_tree_desc_lock);
+    desc = find_irq_desc(&desc_root, irq);
+    spin_unlock(&rb_tree_desc_lock);
+
+    return desc;
 }
 
-int __init arch_init_one_irq_desc(struct irq_desc *desc)
+int arch_init_one_irq_desc(struct irq_desc *desc)
 {
     desc->arch.type = DT_IRQ_TYPE_INVALID;
     return 0;
 }
 
-
-static int __init init_irq_data(void)
+static int init_irq_data(int irq, struct irq_desc *desc)
 {
-    int irq;
-
-    for (irq = NR_LOCAL_IRQS; irq < NR_IRQS; irq++) {
-        struct irq_desc *desc = irq_to_desc(irq);
-        init_one_irq_desc(desc);
-        desc->irq = irq;
-        desc->action  = NULL;
-    }
-
+   init_one_irq_desc(desc);
+   desc->irq = irq;
+   desc->action  = NULL;
+ 
     return 0;
 }
 
@@ -114,7 +117,8 @@ void __init init_IRQ(void)
     spin_unlock(&local_irqs_type_lock);
 
     BUG_ON(init_local_irq_data() < 0);
-    BUG_ON(init_irq_data() < 0);
+
+    desc_root = RB_ROOT;
 }
 
 void __cpuinit init_secondary_IRQ(void)
@@ -265,6 +269,7 @@ void release_irq(unsigned int irq, const void *dev_id)
 
     desc = irq_to_desc(irq);
 
+    ASSERT(desc != NULL);
     spin_lock_irqsave(&desc->lock,flags);
 
     action_ptr = &desc->action;
@@ -301,6 +306,11 @@ void release_irq(unsigned int irq, const void *dev_id)
 
     if ( action->free_on_release )
         xfree(action);
+
+    spin_lock(&rb_tree_desc_lock);
+    delete_irq_desc(&desc_root, irq);
+    xfree(desc);
+    spin_unlock(&rb_tree_desc_lock);
 }
 
 static int __setup_irq(struct irq_desc *desc, unsigned int irqflags,
@@ -339,6 +349,8 @@ int setup_irq(unsigned int irq, unsigned int irqflags, 
struct irqaction *new)
 
     desc = irq_to_desc(irq);
 
+    ASSERT(desc != NULL);
+
     spin_lock_irqsave(&desc->lock, flags);
 
     if ( test_bit(_IRQ_GUEST, &desc->status) )
@@ -382,7 +394,7 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
                        const char * devname)
 {
     struct irqaction *action;
-    struct irq_desc *desc = irq_to_desc(irq);
+    struct irq_desc *desc = NULL;
     unsigned long flags;
     int retval = 0;
 
@@ -394,6 +406,23 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
     action->name = devname;
     action->free_on_release = 1;
 
+    spin_lock(&rb_tree_desc_lock);
+    desc = find_irq_desc(&desc_root, irq);
+
+    if ( desc == NULL )
+    {
+        /* Allocate descriptor and add to rb tree */
+        desc = xzalloc(struct irq_desc);
+        if ( desc == NULL )
+        {
+            spin_unlock(&rb_tree_desc_lock);
+            return -ENOMEM;
+        }
+        init_irq_data(irq, desc);
+        insert_irq_desc(&desc_root, irq, desc);
+    }
+    spin_unlock(&rb_tree_desc_lock);
+
     spin_lock_irqsave(&desc->lock, flags);
 
     /* If the IRQ is already used by someone
@@ -470,13 +499,16 @@ static bool_t irq_validate_new_type(unsigned int curr, 
unsigned new)
 int irq_set_spi_type(unsigned int spi, unsigned int type)
 {
     unsigned long flags;
-    struct irq_desc *desc = irq_to_desc(spi);
+    struct irq_desc *desc = NULL;
     int ret = -EBUSY;
 
     /* This function should not be used for other than SPIs */
     if ( spi < NR_LOCAL_IRQS )
         return -EINVAL;
 
+    desc = irq_to_desc(spi);
+    ASSERT(desc != NULL);
+
     spin_lock_irqsave(&desc->lock, flags);
 
     if ( !irq_validate_new_type(desc->arch.type, type) )
@@ -532,6 +564,7 @@ int platform_get_irq(const struct dt_device_node *device, 
int index)
 {
     struct dt_irq dt_irq;
     unsigned int type, irq;
+    struct irq_desc *desc;
     int res;
 
     res = dt_device_get_irq(device, index, &dt_irq);
@@ -541,6 +574,22 @@ int platform_get_irq(const struct dt_device_node *device, 
int index)
     irq = dt_irq.irq;
     type = dt_irq.type;
 
+    spin_lock(&rb_tree_desc_lock);
+    desc = find_irq_desc(&desc_root, irq);
+    if ( desc == NULL )
+    {
+        /* Allocate descriptor for this irq */
+        desc = xzalloc(struct irq_desc);
+        if ( desc == NULL )
+        {
+            spin_unlock(&rb_tree_desc_lock);
+            return -ENOMEM;
+        }
+        init_irq_data(irq, desc);
+        insert_irq_desc(&desc_root, irq, desc);
+    }
+    spin_unlock(&rb_tree_desc_lock);
+
     /* Setup the IRQ type */
     if ( irq < NR_LOCAL_IRQS )
         res = irq_local_set_type(irq, type);
diff --git a/xen/common/irq.c b/xen/common/irq.c
index 3e55dfa..ddf85c5 100644
--- a/xen/common/irq.c
+++ b/xen/common/irq.c
@@ -40,3 +40,61 @@ unsigned int irq_startup_none(struct irq_desc *desc)
 {
     return 0;
 }
+
+irq_desc_t * find_irq_desc( struct rb_root *root_node, int irq)
+{
+    struct rb_node *node = root_node->rb_node;
+
+    while ( node )
+    {
+        irq_desc_t *this;
+
+        this = container_of(node, irq_desc_t, node);
+ 
+        if ( irq < this->irq )
+            node = node->rb_left;
+        else if (irq > this->irq)
+            node = node->rb_right;
+        else
+            return this;
+    }
+ 
+    return NULL;
+}
+
+int insert_irq_desc(struct rb_root *root_node, int irq, struct irq_desc *desc)
+{
+    struct rb_node **new, *parent;
+
+    new = &root_node->rb_node;
+    parent = NULL;
+
+    while ( *new )
+    {
+        irq_desc_t *this;
+
+        this = container_of(*new, irq_desc_t, node);
+ 
+        parent = *new;
+        if ( desc->irq < this->irq )
+            new = &((*new)->rb_left);
+        else if (desc->irq > this->irq)
+            new = &((*new)->rb_right);
+        else
+            return -EEXIST;
+    }
+ 
+    rb_link_node(&desc->node, parent, new);
+    rb_insert_color(&desc->node, root_node);
+
+    return 0;
+}
+
+void delete_irq_desc(struct rb_root *root_node, int irq)
+{
+   struct irq_desc *desc;
+
+   desc = find_irq_desc(root_node, irq);
+   if ( desc )
+      rb_erase(&desc->node, root_node);
+}
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index 9e0155c..d623ce3 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -6,6 +6,7 @@
 #include <xen/spinlock.h>
 #include <xen/time.h>
 #include <xen/list.h>
+#include <xen/rbtree.h>
 #include <asm/regs.h>
 #include <asm/hardirq.h>
 
@@ -83,6 +84,7 @@ struct msi_desc;
  * first field.
  */
 typedef struct irq_desc {
+    struct rb_node node;
     unsigned int status;        /* IRQ status */
     hw_irq_controller *handler;
     struct msi_desc   *msi_desc;
@@ -168,6 +170,10 @@ static inline void set_native_irq_info(unsigned int irq, 
const cpumask_t *mask)
 
 unsigned int set_desc_affinity(struct irq_desc *, const cpumask_t *);
 
+irq_desc_t * find_irq_desc(struct rb_root *root_node, int irq);
+int insert_irq_desc(struct rb_root *root_node, int irq, struct irq_desc *desc);
+void delete_irq_desc(struct rb_root *root_node, int irq);
+
 #ifndef arch_hwdom_irqs
 unsigned int arch_hwdom_irqs(domid_t);
 #endif
-- 
1.7.9.5


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