bitfield.h: add FIELD_FIT() helper
Add a helper for checking at runtime that a value will fit inside
a specified field/mask.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index f6505d8..8b9d6ff 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -63,6 +63,19 @@
})
/**
+ * FIELD_FIT() - check if value fits in the field
+ * @_mask: shifted mask defining the field's length and position
+ * @_val: value to test against the field
+ *
+ * Return: true if @_val can fit inside @_mask, false if @_val is too big.
+ */
+#define FIELD_FIT(_mask, _val) \
+ ({ \
+ __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_FIT: "); \
+ !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
+ })
+
+/**
* FIELD_PREP() - prepare a bitfield element
* @_mask: shifted mask defining the field's length and position
* @_val: value to put in the field