flow: Add flow_sidx_valid() helper

To implement the TCP hash table, we need an invalid (NULL-like) value for
flow_sidx_t.  We use FLOW_SIDX_NONE for that, but for defensiveness, we
treat (usually) anything with an out of bounds flow index the same way.

That's not always done consistently though.  In flow_at_sidx() we open code
a check on the flow index.  In tcp_hash_probe() we instead compare against
FLOW_SIDX_NONE, and in some other places we use the fact that
flow_at_sidx() will return NULL in this case, even if we don't otherwise
need the flow it returns.

Clean this up a bit, by adding an explicit flow_sidx_valid() test function.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/flow.h b/flow.h
index 29ef9f1..d1f49c6 100644
--- a/flow.h
+++ b/flow.h
@@ -177,6 +177,17 @@ static_assert(sizeof(flow_sidx_t) <= sizeof(uint32_t),
 #define FLOW_SIDX_NONE ((flow_sidx_t){ .flow = FLOW_MAX })
 
 /**
+ * flow_sidx_valid() - Test if a sidx is valid
+ * @sidx:	sidx value
+ *
+ * Return: true if @sidx refers to a valid flow & side
+ */
+static inline bool flow_sidx_valid(flow_sidx_t sidx)
+{
+	return sidx.flow < FLOW_MAX;
+}
+
+/**
  * flow_sidx_eq() - Test if two sidx values are equal
  * @a, @b:	sidx values
  *