null: fix compile time warning on OpenBSD

Fix the following warning on OpenBSD 6.2 (gcc 4.2.1).
This can probably be silenced with void** argument and memcpy() too,
but returning a non-void pointer is clearer IMO when the code also
targets C++.

Compiles with regular make/gmake as well as
 # g++ -O2 -g -shared -rdynamic -fPIC -o cpp_null null.c -DFIO_EXTERNAL_ENGINE

--
    CC engines/null.o
engines/null.c: In function 'fio_null_init':
engines/null.c:142: warning: dereferencing type-punned pointer will break strict-aliasing rules

Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/engines/null.c b/engines/null.c
index 8a4d106be75b1879b466dd433ea2469e9bdd8c1b..47f290548ceafb39763b9bfd5cf08a29aa7f2e06 100644 (file)
--- a/engines/null.c
+++ b/engines/null.c
@@ -87,9 +87,9 @@ static void null_cleanup(struct null_data *nd)
        }
 }
 
-static int null_init(struct thread_data *td, struct null_data **nd_ptr)
+static struct null_data *null_init(struct thread_data *td)
 {
-       struct null_data *nd = (struct null_data *) malloc(sizeof(**nd_ptr));
+       struct null_data *nd = (struct null_data *) malloc(sizeof(*nd));
 
        memset(nd, 0, sizeof(*nd));
 
@@ -99,8 +99,7 @@ static int null_init(struct thread_data *td, struct null_data **nd_ptr)
        } else
                td->io_ops->flags |= FIO_SYNCIO;
 
-       *nd_ptr = nd;
-       return 0;
+       return nd;
 }
 
 #ifndef __cplusplus
@@ -139,7 +138,9 @@ static void fio_null_cleanup(struct thread_data *td)
 
 static int fio_null_init(struct thread_data *td)
 {
-       return null_init(td, (struct null_data **)&td->io_ops_data);
+       td->io_ops_data = null_init(td);
+       assert(td->io_ops_data);
+       return 0;
 }
 
 static struct ioengine_ops ioengine = {
@@ -172,7 +173,8 @@ static void fio_exit fio_null_unregister(void)
 struct NullData {
        NullData(struct thread_data *td)
        {
-               null_init(td, &impl_);
+               impl_ = null_init(td);
+               assert(impl_);
        }
 
        ~NullData()