kunit: drop test pointer in string_stream_fragment

We already store the `struct kunit *test` in the string_stream object
itself, so we need don't need to store a copy of this pointer in every
fragment in the stream.

Drop it, getting string_stream_fragment down the bare minimum: a
list_head and the `char *` with the actual fragment.

Signed-off-by: Daniel Latypov <[e-mail]>
Reviewed-by: David Gow <[e-mail]>
Reviewed-by: Brendan Higgins <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

lib/kunit/string-stream.c

···
 	if (!frag)
 		return ERR_PTR(-ENOMEM);
 
-	frag->test = test;
 	frag->fragment = kunit_kmalloc(test, len, gfp);
 	if (!frag->fragment)
 		return ERR_PTR(-ENOMEM);
···
 	return frag;
 }
 
-static void string_stream_fragment_destroy(struct string_stream_fragment *frag)
+static void string_stream_fragment_destroy(struct kunit *test,
+					   struct string_stream_fragment *frag)
 {
 	list_del(&frag->node);
-	kunit_kfree(frag->test, frag->fragment);
-	kunit_kfree(frag->test, frag);
+	kunit_kfree(test, frag->fragment);
+	kunit_kfree(test, frag);
 }
 
 int string_stream_vadd(struct string_stream *stream,
···
 				 frag_container_safe,
 				 &stream->fragments,
 				 node) {
-		string_stream_fragment_destroy(frag_container);
+		string_stream_fragment_destroy(stream->test, frag_container);
 	}
 	stream->length = 0;
 	spin_unlock(&stream->lock);

lib/kunit/string-stream.h

···
 #include <linux/stdarg.h>
 
 struct string_stream_fragment {
-	struct kunit *test;
 	struct list_head node;
 	char *fragment;
 };