Re: [PATCH] scsi: iscsi: Switch to using the new API kobj_to_dev()

[James Bottomley]

On Mon, 2021-03-08 at 11:34 +0800, Jiapeng Chong wrote:
> Fix the following coccicheck warnings:
>
> ./drivers/scsi/scsi_transport_iscsi.c:930:60-61: WARNING opportunity
> for kobj_to_dev().

I have to ask, what is the point of this? container_of is usually
pretty safe ... as in it will detect when you screw up the usage. The
only real misuse you can get is when the input type has an object of
the same name and return type and you got confused between two objects
with this property, but misuses like this resulting in bugs are very,
very rare.

Usually we wrap container_of because the wrapping is a bit shorter as
you can see: kobj_to_dev is about half the size of the container_of
form ... but is there any other reason to do it?

The problem is that container_of is a standard way of doing cast outs
in the kernel and we have hundreds of them. To be precise, in scsi
alone:

jejb@jarvis:~/git/linux/drivers/scsi> git grep container_of|wc -l
496

So we really don't want to encourage wrapping them all because the
churn would be unbelievable and the gain minute. So why should this
one case especially be wrapped when we don't want to wrap the others?

James

[Jiapeng Chong]

Fix the following coccicheck warnings:

./drivers/scsi/scsi_transport_iscsi.c:930:60-61: WARNING opportunity for
kobj_to_dev().

Reported-by: Abaci Robot <ab...@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapen...@linux.alibaba.com>
---
drivers/scsi/scsi_transport_iscsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 91074fd9..a01275e 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -927,7 +927,7 @@ static umode_t iscsi_flashnode_sess_attr_is_visible(struct kobject *kobj,
struct attribute *attr,
int i)
{
- struct device *dev = container_of(kobj, struct device, kobj);
+ struct device *dev = kobj_to_dev(kobj);
struct iscsi_bus_flash_session *fnode_sess =
iscsi_dev_to_flash_session(dev);
struct iscsi_transport *t = fnode_sess->transport;
--
1.8.3.1

[Jiapeng Chong]

Fix the following coccicheck warnings:

./drivers/scsi/scsi_transport_iscsi.c:4453:61-62: WARNING opportunity
for kobj_to_dev().

./drivers/scsi/scsi_transport_iscsi.c:4309:61-62: WARNING opportunity
for kobj_to_dev().

./drivers/scsi/scsi_transport_iscsi.c:4040:61-62: WARNING opportunity

for kobj_to_dev().

Reported-by: Abaci Robot <ab...@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapen...@linux.alibaba.com>
---

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

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 969d24d..debedcd 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -4037,7 +4037,7 @@ static ISCSI_CLASS_ATTR(conn, field, S_IRUGO, \
static umode_t iscsi_conn_attr_is_visible(struct kobject *kobj,

struct attribute *attr, int i)
{

- struct device *cdev = container_of(kobj, struct device, kobj);
+ struct device *cdev = kobj_to_dev(kobj);
struct iscsi_cls_conn *conn = transport_class_to_conn(cdev);
struct iscsi_transport *t = conn->transport;
int param;
@@ -4306,7 +4306,7 @@ static ISCSI_CLASS_ATTR(priv_sess, field, S_IRUGO | S_IWUSR, \
static umode_t iscsi_session_attr_is_visible(struct kobject *kobj,

struct attribute *attr, int i)
{

- struct device *cdev = container_of(kobj, struct device, kobj);
+ struct device *cdev = kobj_to_dev(kobj);
struct iscsi_cls_session *session = transport_class_to_session(cdev);
struct iscsi_transport *t = session->transport;
int param;
@@ -4450,7 +4450,7 @@ static ISCSI_CLASS_ATTR(host, field, S_IRUGO, show_host_param_##param, \
static umode_t iscsi_host_attr_is_visible(struct kobject *kobj,

struct attribute *attr, int i)
{

- struct device *cdev = container_of(kobj, struct device, kobj);
+ struct device *cdev = kobj_to_dev(kobj);
struct Scsi_Host *shost = transport_class_to_shost(cdev);
struct iscsi_internal *priv = to_iscsi_internal(shost->transportt);
int param;
--
1.8.3.1