[PATCH] fs/ceph: Move a dereference below a NULL test

[PATCH] fs/ceph: Move a dereference below a NULL test

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

If the NULL test is necessary, then the dereference should be moved below
the NULL test.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/).

// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
  ... when != E
      when != i
  if (E == NULL) S
+ i = E->fld;
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 fs/ceph/osd_client.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -u -p a/fs/ceph/osd_client.c b/fs/ceph/osd_client.c
--- a/fs/ceph/osd_client.c
+++ b/fs/ceph/osd_client.c
@@ -1244,11 +1244,12 @@ int ceph_osdc_writepages(struct ceph_osd
 static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
 {
 	struct ceph_osd *osd = con->private;
-	struct ceph_osd_client *osdc = osd->o_osdc;
+	struct ceph_osd_client *osdc;
 	int type = le16_to_cpu(msg->hdr.type);
 
 	if (!osd)
 		return;
+	osdc = osd->o_osdc;
 
 	switch (type) {
 	case CEPH_MSG_OSD_MAP:

Re: [ceph-devel] [PATCH] fs/ceph: Move a dereference below a NULL test

[Sage Weil]

On Sat, 21 Nov 2009, Julia Lawall wrote:

> From: Julia Lawall <julia@diku.dk>
> 
> If the NULL test is necessary, then the dereference should be moved below
> the NULL test.

I've applied this (and the previous patch) to the ceph tree.  

Thanks!
sage


> 
> The semantic patch that makes this change is as follows:
> (http://coccinelle.lip6.fr/).
> 
> // <smpl>
> @@
> type T;
> expression E;
> identifier i,fld;
> statement S;
> @@
> 
> - T i = E->fld;
> + T i;
>   ... when != E
>       when != i
>   if (E == NULL) S
> + i = E->fld;
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
>  fs/ceph/osd_client.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff -u -p a/fs/ceph/osd_client.c b/fs/ceph/osd_client.c
> --- a/fs/ceph/osd_client.c
> +++ b/fs/ceph/osd_client.c
> @@ -1244,11 +1244,12 @@ int ceph_osdc_writepages(struct ceph_osd
>  static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
>  {
>  	struct ceph_osd *osd = con->private;
> -	struct ceph_osd_client *osdc = osd->o_osdc;
> +	struct ceph_osd_client *osdc;
>  	int type = le16_to_cpu(msg->hdr.type);
>  
>  	if (!osd)
>  		return;
> +	osdc = osd->o_osdc;
>  
>  	switch (type) {
>  	case CEPH_MSG_OSD_MAP:
> 
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