From: Julia Lawall <julia@diku.dk>

If pgpath->pg->ps.type is NULL, it is not possible to access its name
field. Alasdair G Kergon suggested that the field type is actually known
never to be NULL; instead it is its field reinstate_path that is supposed
to be tested.


This problem was found using the following semantic match
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E, E1;
identifier f;
statement S1,S2,S3;
@@

* if (E == NULL)
{
... when != if (E == NULL) S1 else S2
when != E = E1
* E->f
... when any
return ...;
}
else S3
// </smpl>

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

---

diff -u -p a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -883,7 +883,7 @@ static int reinstate_path(struct pgpath
if (pgpath->path.is_active)
goto out;

- if (!pgpath->pg->ps.type) {
+ if (!pgpath->pg->ps.type->reinstate_path) {
DMWARN("Reinstate path not supported by path selector %s",
pgpath->pg->ps.type->name);
r = -EINVAL;

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