scsi: mvsas: use struct_size() in kzalloc()

One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

---
 drivers/scsi/mvsas/mv_init.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 030d911ee374..cd6ba7ed0ab4 100644
@@ -366,9 +366,9 @@ static struct mvs_info *mvs_pci_alloc(struct pci_dev *pdev,
 	struct mvs_info *mvi = NULL;
 	struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);
 
-	mvi = kzalloc(sizeof(*mvi) +
-		(1L << mvs_chips[ent->driver_data].slot_width) *
-		sizeof(struct mvs_slot_info), GFP_KERNEL);
+	mvi = kzalloc(struct_size(mvi, slot_info,
+		      (1L << mvs_chips[ent->driver_data].slot_width)),
+		      GFP_KERNEL);
 	if (!mvi)
 		return NULL;
 

2.20.1