genirq: Make sparse_irq_lock protect what it should protect

[pandora-kernel.git] / kernel / irq / irqdesc.c

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index d86e254..a8cad80 100644 (file)
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -130,6 +130,16 @@ static void free_masks(struct irq_desc *desc)
 static inline void free_masks(struct irq_desc *desc) { }
 #endif
 
+void irq_lock_sparse(void)
+{
+       mutex_lock(&sparse_irq_lock);
+}
+
+void irq_unlock_sparse(void)
+{
+       mutex_unlock(&sparse_irq_lock);
+}
+
 static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
 {
        struct irq_desc *desc;
@@ -166,9 +176,13 @@ static void free_desc(unsigned int irq)
 
        unregister_irq_proc(irq, desc);
 
-       mutex_lock(&sparse_irq_lock);
+       /*
+        * sparse_irq_lock protects also show_interrupts() and
+        * kstat_irq_usr(). Once we deleted the descriptor from the
+        * sparse tree we can free it. Access in proc will fail to
+        * lookup the descriptor.
+        */
        delete_irq_desc(irq);
-       mutex_unlock(&sparse_irq_lock);
 
        free_masks(desc);
        free_percpu(desc->kstat_irqs);
@@ -185,19 +199,14 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,
                desc = alloc_desc(start + i, node, owner);
                if (!desc)
                        goto err;
-               mutex_lock(&sparse_irq_lock);
                irq_insert_desc(start + i, desc);
-               mutex_unlock(&sparse_irq_lock);
        }
+       bitmap_set(allocated_irqs, start, cnt);
        return start;
 
 err:
        for (i--; i >= 0; i--)
                free_desc(start + i);
-
-       mutex_lock(&sparse_irq_lock);
-       bitmap_clear(allocated_irqs, start, cnt);
-       mutex_unlock(&sparse_irq_lock);
        return -ENOMEM;
 }
 
@@ -289,6 +298,7 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
 
                desc->owner = owner;
        }
+       bitmap_set(allocated_irqs, start, cnt);
        return start;
 }
 
@@ -329,10 +339,10 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
        if (from >= nr_irqs || (from + cnt) > nr_irqs)
                return;
 
+       mutex_lock(&sparse_irq_lock);
        for (i = 0; i < cnt; i++)
                free_desc(from + i);
 
-       mutex_lock(&sparse_irq_lock);
        bitmap_clear(allocated_irqs, from, cnt);
        mutex_unlock(&sparse_irq_lock);
 }
@@ -369,19 +379,15 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
                                           from, cnt, 0);
        ret = -EEXIST;
        if (irq >=0 && start != irq)
-               goto err;
+               goto unlock;
 
        if (start + cnt > nr_irqs) {
                ret = irq_expand_nr_irqs(start + cnt);
                if (ret)
-                       goto err;
+                       goto unlock;
        }
-
-       bitmap_set(allocated_irqs, start, cnt);
-       mutex_unlock(&sparse_irq_lock);
-       return alloc_descs(start, cnt, node, owner);
-
-err:
+       ret = alloc_descs(start, cnt, node, owner);
+unlock:
        mutex_unlock(&sparse_irq_lock);
        return ret;
 }
@@ -487,6 +493,15 @@ void dynamic_irq_cleanup(unsigned int irq)
        raw_spin_unlock_irqrestore(&desc->lock, flags);
 }
 
+/**
+ * kstat_irqs_cpu - Get the statistics for an interrupt on a cpu
+ * @irq:       The interrupt number
+ * @cpu:       The cpu number
+ *
+ * Returns the sum of interrupt counts on @cpu since boot for
+ * @irq. The caller must ensure that the interrupt is not removed
+ * concurrently.
+ */
 unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 {
        struct irq_desc *desc = irq_to_desc(irq);
@@ -495,6 +510,14 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
                        *per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
 }
 
+/**
+ * kstat_irqs - Get the statistics for an interrupt
+ * @irq:       The interrupt number
+ *
+ * Returns the sum of interrupt counts on all cpus since boot for
+ * @irq. The caller must ensure that the interrupt is not removed
+ * concurrently.
+ */
 unsigned int kstat_irqs(unsigned int irq)
 {
        struct irq_desc *desc = irq_to_desc(irq);
@@ -507,3 +530,22 @@ unsigned int kstat_irqs(unsigned int irq)
                sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
        return sum;
 }
+
+/**
+ * kstat_irqs_usr - Get the statistics for an interrupt
+ * @irq:       The interrupt number
+ *
+ * Returns the sum of interrupt counts on all cpus since boot for
+ * @irq. Contrary to kstat_irqs() this can be called from any
+ * preemptible context. It's protected against concurrent removal of
+ * an interrupt descriptor when sparse irqs are enabled.
+ */
+unsigned int kstat_irqs_usr(unsigned int irq)
+{
+       int sum;
+
+       irq_lock_sparse();
+       sum = kstat_irqs(irq);
+       irq_unlock_sparse();
+       return sum;
+}