linuxlist.h: add llist_count()

After subchan_demux.c in libosmo-abis, osmo-bts/common/vty.c and openbsc's
gtphub_test.c, more places would like to count the llist items (mostly unit
tests). Instead of proliferating numerous local implementations, add here.

NOTE: other than the previous llist_len() implementations, this one returns an
*unsigned* length, which might need some adjusting of current callers.

Call this llist_count() rather than llist_len() to highlight the fact that this
is actively iterating. This also avoids a potential naming conflict when
library versions mismatch.

Change-Id: Ic49adc7a346f5722bf624d7d3b4a735e4220ae15

1 files changed, 16 insertions, 0 deletions

diff --git a/include/osmocom/core/linuxlist.h b/include/osmocom/core/linuxlist.h
index 1c833950..affa8273 100644
--- a/include/osmocom/core/linuxlist.h
+++ b/include/osmocom/core/linuxlist.h
@@ -351,6 +351,22 @@ static inline void llist_splice_init(struct llist_head *llist,
 	for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
         	(pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next))
 
+/*! \brief count nr of llist items by iterating.
+ *  \param head The llist head to count items of.
+ *  \returns Number of items.
+ *
+ * This function is not efficient, mostly useful for small lists and non time
+ * critical cases like unit tests.
+ */
+static inline unsigned int llist_count(struct llist_head *head)
+{
+	struct llist_head *entry;
+	unsigned int i = 0;
+	llist_for_each(entry, head)
+		i++;
+	return i;
+}
+
 /*!
  *  }@
  */