[PATCH] scsi: virtio_scsi: Use struct_size() helper

From: Gustavo A. R. Silva
Date: Wed Jun 19 2019 - 15:33:48 EST


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 virtio_scsi {
...
struct virtio_scsi_vq req_vqs[];
};

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues

with:

struct_size(vscsi, req_vqs, num_queues)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/scsi/virtio_scsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 13f1b3b9923a..ed4f79bffc73 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -795,7 +795,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
num_targets = virtscsi_config_get(vdev, max_target) + 1;

shost = scsi_host_alloc(&virtscsi_host_template,
- sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues);
+ struct_size(vscsi, req_vqs, num_queues));
if (!shost)
return -ENOMEM;

--
2.21.0