[PATCH 1/3] ida: Introduce ida_weight()

[Michal Wajdeczko]

There might be a case when driver will need to estimate
saturation of used IDs.  Add helper function that will
calculate number of allocated IDs in the IDA.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
---
 include/linux/idr.h |  1 +
 lib/idr.c           | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index a0dce14090a9..f477e35c9619 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -255,6 +255,7 @@ struct ida {
 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
 void ida_free(struct ida *, unsigned int id);
 void ida_destroy(struct ida *ida);
+unsigned long ida_weight(struct ida *ida);
 
 /**
  * ida_alloc() - Allocate an unused ID.
diff --git a/lib/idr.c b/lib/idr.c
index 13f2758c2377..ed987a0fc25a 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -554,6 +554,31 @@ void ida_destroy(struct ida *ida)
 }
 EXPORT_SYMBOL(ida_destroy);
 
+/**
+ * ida_weight() - Calculate number of allocated IDs.
+ * @ida: IDA handle.
+ *
+ * Return: Number of allocated IDs in this IDA.
+ */
+unsigned long ida_weight(struct ida *ida)
+{
+	XA_STATE(xas, &ida->xa, 0);
+	struct ida_bitmap *bitmap;
+	unsigned long weight = 0;
+	unsigned long flags;
+
+	xas_lock_irqsave(&xas, flags);
+	xas_for_each(&xas, bitmap, ULONG_MAX) {
+		weight += xa_is_value(bitmap) ?
+			hweight_long(xa_to_value(bitmap)) :
+			bitmap_weight(bitmap->bitmap, IDA_BITMAP_BITS);
+	}
+	xas_unlock_irqrestore(&xas, flags);
+
+	return weight;
+}
+EXPORT_SYMBOL(ida_weight);
+
 #ifndef __KERNEL__
 extern void xa_dump_index(unsigned long index, unsigned int shift);
 #define IDA_CHUNK_SHIFT		ilog2(IDA_BITMAP_BITS)
-- 
2.25.1