[PATCH 6/8] irq: Add new reserved_irqs clear/mark functions

[Yinghai Lu]

Prepare for ioapic hotplug.

Signed-off-by: Yinghai Lu <ying...@kernel.org>
---
 include/linux/irq.h  |  3 +++
 kernel/irq/irqdesc.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 02dc0e4..2ba3245 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -603,6 +603,9 @@ static inline u32 irq_get_trigger_type(unsigned int irq)
        return d ? irqd_get_trigger_type(d) : 0;
 }
 
+int irq_clear_reserved_irqs(unsigned int from, unsigned int cnt);
+int irq_mark_reserved_irqs(int irq, unsigned int from, unsigned int cnt);
+
 int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
                struct module *owner);
 
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 49bf891..865ebc0 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -97,6 +97,7 @@ int nr_irqs = NR_IRQS;
 EXPORT_SYMBOL_GPL(nr_irqs);
 
 static DEFINE_MUTEX(sparse_irq_lock);
+static DECLARE_BITMAP(reserved_irqs, IRQ_BITMAP_BITS);
 static DECLARE_BITMAP(allocated_irqs, IRQ_BITMAP_BITS);
 
 #ifdef CONFIG_SPARSE_IRQ
@@ -400,6 +401,73 @@ err:
 EXPORT_SYMBOL_GPL(__irq_alloc_descs);
 
 /**
+ * irq_clear_reserved_irqs - clear irqs reserved
+ * @from:      clear from irq number
+ * @cnt:       number of irqs to clear
+ *
+ * Returns 0 on success or an appropriate error code
+ */
+int irq_clear_reserved_irqs(unsigned int from, unsigned int cnt)
+{
+       if (!cnt || (from + cnt) > nr_irqs)
+               return -EINVAL;
+
+       mutex_lock(&sparse_irq_lock);
+       bitmap_clear(reserved_irqs, from, cnt);
+       mutex_unlock(&sparse_irq_lock);
+
+       return 0;
+}
+
+/**
+ * irq_mark_reserved_irqs - mark irqs reserved
+ * @irq:       Allocate for specific irq number if irq >= 0
+ * @from:      mark from irq number
+ * @cnt:       number of irqs to mark
+ *
+ * Returns the first irq number or error code
+ */
+int irq_mark_reserved_irqs(int irq, unsigned int from, unsigned int cnt)
+{
+       unsigned int start, reserve;
+       int ret;
+
+       if (!cnt)
+               return -EINVAL;
+
+       if (irq >= 0) {
+               if (from > irq)
+                       return -EINVAL;
+               from = irq;
+       }
+
+       mutex_lock(&sparse_irq_lock);
+       start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
+                                               from, cnt, 0);
+       ret = -EEXIST;
+       if (irq >= 0 && start != irq)
+               goto err;
+
+       if (start + cnt > nr_irqs) {
+               ret = irq_expand_nr_irqs(start + cnt);
+               if (ret)
+                       goto err;
+       }
+
+       reserve = bitmap_find_next_zero_area(reserved_irqs, nr_irqs, start,
+                                               cnt, 0);
+       if (reserve == start) {
+               ret = start;
+               bitmap_set(reserved_irqs, start, cnt);
+       } else
+               ret = -EEXIST;
+
+err:
+       mutex_unlock(&sparse_irq_lock);
+       return ret;
+}
+
+/**
  * irq_get_next_irq - get next allocated irq number
  * @offset:    where to start the search
  *
-- 
1.8.4.5

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