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authorThomas Gleixner <tglx@linutronix.de>2010-09-27 17:48:26 +0200
committerThomas Gleixner <tglx@linutronix.de>2010-10-12 16:39:07 +0200
commit1f5a5b87f78fade3ae48dfd55e8765d1d622ea4e (patch)
tree762a5dbf40129ffd9667a170b2503a77c95320f7 /kernel/irq
parent1318a481fc37c503a901b96ae06b692ca2b21af5 (diff)
downloadop-kernel-dev-1f5a5b87f78fade3ae48dfd55e8765d1d622ea4e.zip
op-kernel-dev-1f5a5b87f78fade3ae48dfd55e8765d1d622ea4e.tar.gz
genirq: Implement a sane sparse_irq allocator
The current sparse_irq allocator has several short comings due to failures in the design or the lack of it: - Requires iteration over the number of active irqs to find a free slot (Some architectures have grown their own workarounds for this) - Removal of entries is not possible - Racy between create_irq_nr and destroy_irq (plugged by horrible callbacks) - Migration of active irq descriptors is not possible - No bulk allocation of irq ranges - Sprinkeled irq_desc references all over the place outside of kernel/irq/ (The previous chip functions series is addressing this issue) Implement a sane allocator which fixes the above short comings (though migration of active descriptors needs a full tree wide cleanup of the direct and mostly unlocked access to irq_desc). The new allocator still uses a radix_tree, but uses a bitmap for keeping track of allocated irq numbers. That allows: - Fast lookup of a free slot - Allows the removal of descriptors - Prevents the create/destroy race - Bulk allocation of consecutive irq ranges - Basic design is ready for migration of life descriptors after further cleanups The bitmap is also used in the SPARSE_IRQ=n case for lookup and raceless (de)allocation of irq numbers. So it removes the requirement for looping through the descriptor array to find slots. Right now it uses sparse_irq_lock to protect the bitmap and the radix tree, but after cleaning up all users we should be able convert that to a mutex and to switch the radix_tree and decriptor allocations to GFP_KERNEL. [ Folded in a bugfix from Yinghai Lu ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/irqdesc.c231
1 files changed, 223 insertions, 8 deletions
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 29963f9..4eea48b 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -13,6 +13,7 @@
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/radix-tree.h>
+#include <linux/bitmap.h>
#include "internals.h"
@@ -33,9 +34,54 @@ static void __init init_irq_default_affinity(void)
}
#endif
+#ifdef CONFIG_SMP
+static int alloc_masks(struct irq_desc *desc, gfp_t gfp, int node)
+{
+ if (!zalloc_cpumask_var_node(&desc->irq_data.affinity, gfp, node))
+ return -ENOMEM;
+
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+ if (!zalloc_cpumask_var_node(&desc->pending_mask, gfp, node)) {
+ free_cpumask_var(desc->irq_data.affinity);
+ return -ENOMEM;
+ }
+#endif
+ return 0;
+}
+
+static void desc_smp_init(struct irq_desc *desc, int node)
+{
+ desc->node = node;
+ cpumask_copy(desc->irq_data.affinity, irq_default_affinity);
+}
+
+#else
+static inline int
+alloc_masks(struct irq_desc *desc, gfp_t gfp, int node) { return 0; }
+static inline void desc_smp_init(struct irq_desc *desc, int node) { }
+#endif
+
+static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node)
+{
+ desc->irq_data.irq = irq;
+ desc->irq_data.chip = &no_irq_chip;
+ desc->irq_data.chip_data = NULL;
+ desc->irq_data.handler_data = NULL;
+ desc->irq_data.msi_desc = NULL;
+ desc->status = IRQ_DEFAULT_INIT_FLAGS;
+ desc->handle_irq = handle_bad_irq;
+ desc->depth = 1;
+ desc->name = NULL;
+ memset(desc->kstat_irqs, 0, nr_cpu_ids * sizeof(*(desc->kstat_irqs)));
+ desc_smp_init(desc, node);
+}
+
int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);
+DEFINE_RAW_SPINLOCK(sparse_irq_lock);
+static DECLARE_BITMAP(allocated_irqs, NR_IRQS);
+
#ifdef CONFIG_SPARSE_IRQ
static struct irq_desc irq_desc_init = {
@@ -85,14 +131,9 @@ static void init_one_irq_desc(int irq, struct irq_desc *desc, int node)
arch_init_chip_data(desc, node);
}
-/*
- * Protect the sparse_irqs:
- */
-DEFINE_RAW_SPINLOCK(sparse_irq_lock);
-
static RADIX_TREE(irq_desc_tree, GFP_ATOMIC);
-static void set_irq_desc(unsigned int irq, struct irq_desc *desc)
+static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
{
radix_tree_insert(&irq_desc_tree, irq, desc);
}
@@ -111,6 +152,94 @@ void replace_irq_desc(unsigned int irq, struct irq_desc *desc)
radix_tree_replace_slot(ptr, desc);
}
+static void delete_irq_desc(unsigned int irq)
+{
+ radix_tree_delete(&irq_desc_tree, irq);
+}
+
+#ifdef CONFIG_SMP
+static void free_masks(struct irq_desc *desc)
+{
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+ free_cpumask_var(desc->pending_mask);
+#endif
+ free_cpumask_var(desc->affinity);
+}
+#else
+static inline void free_masks(struct irq_desc *desc) { }
+#endif
+
+static struct irq_desc *alloc_desc(int irq, int node)
+{
+ struct irq_desc *desc;
+ gfp_t gfp = GFP_KERNEL;
+
+ desc = kzalloc_node(sizeof(*desc), gfp, node);
+ if (!desc)
+ return NULL;
+ /* allocate based on nr_cpu_ids */
+ desc->kstat_irqs = kzalloc_node(nr_cpu_ids * sizeof(*desc->kstat_irqs),
+ gfp, node);
+ if (!desc->kstat_irqs)
+ goto err_desc;
+
+ if (alloc_masks(desc, gfp, node))
+ goto err_kstat;
+
+ raw_spin_lock_init(&desc->lock);
+ lockdep_set_class(&desc->lock, &irq_desc_lock_class);
+
+ desc_set_defaults(irq, desc, node);
+
+ return desc;
+
+err_kstat:
+ kfree(desc->kstat_irqs);
+err_desc:
+ kfree(desc);
+ return NULL;
+}
+
+static void free_desc(unsigned int irq)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+ delete_irq_desc(irq);
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+
+ free_masks(desc);
+ kfree(desc->kstat_irqs);
+ kfree(desc);
+}
+
+static int alloc_descs(unsigned int start, unsigned int cnt, int node)
+{
+ struct irq_desc *desc;
+ unsigned long flags;
+ int i;
+
+ for (i = 0; i < cnt; i++) {
+ desc = alloc_desc(start + i, node);
+ if (!desc)
+ goto err;
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+ irq_insert_desc(start + i, desc);
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ }
+ return start;
+
+err:
+ for (i--; i >= 0; i--)
+ free_desc(start + i);
+
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+ bitmap_clear(allocated_irqs, start, cnt);
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ return -ENOMEM;
+}
+
static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS_LEGACY-1] = {
.status = IRQ_DEFAULT_INIT_FLAGS,
@@ -155,7 +284,7 @@ int __init early_irq_init(void)
lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
alloc_desc_masks(&desc[i], node, true);
init_desc_masks(&desc[i]);
- set_irq_desc(i, &desc[i]);
+ irq_insert_desc(i, &desc[i]);
}
return arch_early_irq_init();
@@ -192,7 +321,7 @@ struct irq_desc * __ref irq_to_desc_alloc_node(unsigned int irq, int node)
}
init_one_irq_desc(irq, desc, node);
- set_irq_desc(irq, desc);
+ irq_insert_desc(irq, desc);
out_unlock:
raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
@@ -245,8 +374,94 @@ struct irq_desc *irq_to_desc_alloc_node(unsigned int irq, int node)
{
return irq_to_desc(irq);
}
+
+#ifdef CONFIG_SMP
+static inline int desc_node(struct irq_desc *desc)
+{
+ return desc->irq_data.node;
+}
+#else
+static inline int desc_node(struct irq_desc *desc) { return 0; }
+#endif
+
+static void free_desc(unsigned int irq)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&desc->lock, flags);
+ desc_set_defaults(irq, desc, desc_node(desc));
+ raw_spin_unlock_irqrestore(&desc->lock, flags);
+}
+
+static inline int alloc_descs(unsigned int start, unsigned int cnt, int node)
+{
+ return start;
+}
#endif /* !CONFIG_SPARSE_IRQ */
+/* Dynamic interrupt handling */
+
+/**
+ * irq_free_descs - free irq descriptors
+ * @from: Start of descriptor range
+ * @cnt: Number of consecutive irqs to free
+ */
+void irq_free_descs(unsigned int from, unsigned int cnt)
+{
+ unsigned long flags;
+ int i;
+
+ if (from >= nr_irqs || (from + cnt) > nr_irqs)
+ return;
+
+ for (i = 0; i < cnt; i++)
+ free_desc(from + i);
+
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+ bitmap_clear(allocated_irqs, from, cnt);
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+}
+
+/**
+ * irq_alloc_descs - allocate and initialize a range of irq descriptors
+ * @irq: Allocate for specific irq number if irq >= 0
+ * @from: Start the search from this irq number
+ * @cnt: Number of consecutive irqs to allocate.
+ * @node: Preferred node on which the irq descriptor should be allocated
+ *
+ * Returns the first irq number or error code
+ */
+int __ref
+irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node)
+{
+ unsigned long flags;
+ int start, ret;
+
+ if (!cnt)
+ return -EINVAL;
+
+ raw_spin_lock_irqsave(&sparse_irq_lock, flags);
+
+ start = bitmap_find_next_zero_area(allocated_irqs, nr_irqs, from, cnt, 0);
+ ret = -EEXIST;
+ if (irq >=0 && start != irq)
+ goto err;
+
+ ret = -ENOMEM;
+ if (start >= nr_irqs)
+ goto err;
+
+ bitmap_set(allocated_irqs, start, cnt);
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ return alloc_descs(start, cnt, node);
+
+err:
+ raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ return ret;
+}
+
+/* Statistics access */
void clear_kstat_irqs(struct irq_desc *desc)
{
memset(desc->kstat_irqs, 0, nr_cpu_ids * sizeof(*(desc->kstat_irqs)));
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