[PATCH v2 1/3] scsi: iscsi: Add helper functions to manage iscsi_cls_conn

[Wenchao Hao]

iscsi_alloc_conn(): alloc and initialize iscsi_cls_conn
iscsi_add_conn(): expose iscsi_cls_conn to userspace's via sysfs.
iscsi_remove_conn(): remove iscsi_cls_conn from sysfs
iscsi_free_conn(): free iscsi_cls_conn

Signed-off-by: Wenchao Hao <haowe...@huawei.com>
Signed-off-by: Wu Bo <wub...@huawei.com>
---
drivers/scsi/scsi_transport_iscsi.c | 107 ++++++++++++++++++++++++++++
include/scsi/scsi_transport_iscsi.h | 5 ++
2 files changed, 112 insertions(+)

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 554b6f784223..8e97c6f88359 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2340,6 +2340,113 @@ void iscsi_free_session(struct iscsi_cls_session *session)
}
EXPORT_SYMBOL_GPL(iscsi_free_session);

+/**
+ * iscsi_alloc_conn - alloc iscsi class connection
+ * @session: iscsi cls session
+ * @dd_size: private driver data size
+ * @cid: connection id
+ *
+ * This can be called from a LLD or iscsi_transport. The connection
+ * is child of the session so cid must be unique for all connections
+ * on the session.
+ *
+ * Since we do not support MCS, cid will normally be zero. In some cases
+ * for software iscsi we could be trying to preallocate a connection struct
+ * in which case there could be two connection structs and cid would be
+ * non-zero.
+ */
+struct iscsi_cls_conn *
+iscsi_alloc_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
+{
+ struct iscsi_transport *transport = session->transport;
+ struct iscsi_cls_conn *conn;
+
+ conn = kzalloc(sizeof(*conn) + dd_size, GFP_KERNEL);
+ if (!conn)
+ return NULL;
+ if (dd_size)
+ conn->dd_data = &conn[1];
+
+ mutex_init(&conn->ep_mutex);
+ INIT_LIST_HEAD(&conn->conn_list);
+ INIT_WORK(&conn->cleanup_work, iscsi_cleanup_conn_work_fn);
+ conn->transport = transport;
+ conn->cid = cid;
+ conn->state = ISCSI_CONN_DOWN;
+
+ /* this is released in the dev's release function */
+ if (!get_device(&session->dev))
+ goto free_conn;
+
+ dev_set_name(&conn->dev, "connection%d:%u", session->sid, cid);
+ device_initialize(&conn->dev);
+ conn->dev.parent = &session->dev;
+ conn->dev.release = iscsi_conn_release;
+
+ return conn;
+
+free_conn:
+ kfree(conn);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(iscsi_alloc_conn);
+
+/**
+ * iscsi_add_conn - add iscsi class connection
+ * @conn: iscsi cls connection
+ *
+ * this would expose iscsi_cls_conn to sysfs, so make sure the related
+ * resources when access sysfs attributes are initialized before calling this.
+ */
+int iscsi_add_conn(struct iscsi_cls_conn *conn)
+{
+ int err;
+ unsigned long flags;
+ struct iscsi_cls_session *session = iscsi_dev_to_session(conn->dev.parent);
+
+ err = device_add(&conn->dev);
+ if (err) {
+ iscsi_cls_session_printk(KERN_ERR, session,
+ "could not register connection's dev\n");
+ put_device(&session->dev);
+ return err;
+ }
+ err = transport_register_device(&conn->dev);
+ if (err) {
+ iscsi_cls_session_printk(KERN_ERR, session,
+ "could not register transport's dev\n");
+ device_del(&conn->dev);
+ put_device(&session->dev);
+ return err;
+ }
+
+ spin_lock_irqsave(&connlock, flags);
+ list_add(&conn->conn_list, &connlist);
+ spin_unlock_irqrestore(&connlock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iscsi_add_conn);
+
+/**
+ * iscsi_remove_conn - remove iscsi class connection from sysfs
+ * @conn: iscsi cls connection
+ *
+ * this would remove iscsi_cls_conn from sysfs, and wait for previous
+ * read/write of iscsi_cls_conn's attributes in sysfs finishing
+ */
+void iscsi_remove_conn(struct iscsi_cls_conn *conn)
+{
+ device_del(&conn->dev);
+}
+EXPORT_SYMBOL_GPL(iscsi_remove_conn);
+
+void iscsi_free_conn(struct iscsi_cls_conn *conn)
+{
+ put_device(&conn->dev);
+}
+EXPORT_SYMBOL_GPL(iscsi_free_conn);
+
/**
* iscsi_create_conn - create iscsi class connection
* @session: iscsi cls session
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index c5d7810fd792..346f65bc3861 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -441,6 +441,11 @@ extern struct iscsi_cls_session *iscsi_create_session(struct Scsi_Host *shost,
unsigned int target_id);
extern void iscsi_remove_session(struct iscsi_cls_session *session);
extern void iscsi_free_session(struct iscsi_cls_session *session);
+extern struct iscsi_cls_conn *iscsi_alloc_conn(struct iscsi_cls_session *sess,
+ int dd_size, uint32_t cid);
+extern int iscsi_add_conn(struct iscsi_cls_conn *conn);
+extern void iscsi_remove_conn(struct iscsi_cls_conn *conn);
+extern void iscsi_free_conn(struct iscsi_cls_conn *conn);
extern struct iscsi_cls_conn *iscsi_create_conn(struct iscsi_cls_session *sess,
int dd_size, uint32_t cid);
extern void iscsi_put_conn(struct iscsi_cls_conn *conn);
--
2.32.0

[Mike Christie]

Is that with the upstream iscsi tools or your version? I don't think the comment
is needed or is needed somewhere else.

If this happens then they will have the same sysfs/device name so when we do the
device_add it will spit an error about duplicate names.

I would call iscsi_free_conn. instead of put_device.

> + return err;
> + }
> + err = transport_register_device(&conn->dev);
> + if (err) {
> + iscsi_cls_session_printk(KERN_ERR, session,
> + "could not register transport's dev\n");
> + device_del(&conn->dev);
> + put_device(&session->dev);

Is for the get_device(&session->dev) in iscsi_alloc_conn? If so you don't need to
do it because when the last put is done on the conn->dev, it will call
iscsi_conn_release which does the put on the session when it does "put_device(parent).

Or did you mean to call put_device on the conn->dev?

I would do device_el(&conn->dev) then do a goto free_conn at the bottom which
does iscsi_free_conn. The place above should do the goto as well.

> + return err;
> + }
> +
> + spin_lock_irqsave(&connlock, flags);
> + list_add(&conn->conn_list, &connlist);
> + spin_unlock_irqrestore(&connlock, flags);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(iscsi_add_conn);
> +
> +/**
> + * iscsi_remove_conn - remove iscsi class connection from sysfs
> + * @conn: iscsi cls connection
> + *
> + * this would remove iscsi_cls_conn from sysfs, and wait for previous
> + * read/write of iscsi_cls_conn's attributes in sysfs finishing
> + */
> +void iscsi_remove_conn(struct iscsi_cls_conn *conn)
> +{
> + device_del(&conn->dev);

This should have the guts of iscsi_destroy_conn which reverses what
the iscsi_add_conn did:

spin_lock_irqsave(&connlock, flags);
list_del(&conn->conn_list);
spin_unlock_irqrestore(&connlock, flags);

transport_unregister_device(&conn->dev);

device_del(&conn->dev).

You can then kill iscsi_destroy_conn.

> +}
> +EXPORT_SYMBOL_GPL(iscsi_remove_conn);
> +
> +void iscsi_free_conn(struct iscsi_cls_conn *conn)
> +{
> + put_device(&conn->dev);
> +}
> +EXPORT_SYMBOL_GPL(iscsi_free_conn);

Sorry I made a mistake with this suggestion. Kill this and just have
the user do iscsi_put_conn.

[Wenchao Hao]

Sorry I noticed it but forget to remove it. Here should not call
put_device() or iscsi_free_conn(). If iscsi_add_conn() failed, we shoule
not call any put operation which might cause resource free.

>> + return err;
>> + }
>> + err = transport_register_device(&conn->dev);
>> + if (err) {
>> + iscsi_cls_session_printk(KERN_ERR, session,
>> + "could not register transport's dev\n");
>> + device_del(&conn->dev);
>> + put_device(&session->dev);
>
>
> Is for the get_device(&session->dev) in iscsi_alloc_conn? If so you don't need to
> do it because when the last put is done on the conn->dev, it will call
> iscsi_conn_release which does the put on the session when it does "put_device(parent).
>
> Or did you mean to call put_device on the conn->dev?
>

As above, we shouldn't call put_device() here.

[Wenchao Hao]

iscsi_alloc_conn(): alloc and initialize iscsi_cls_conn
iscsi_add_conn(): expose iscsi_cls_conn to userspace's via sysfs.
iscsi_remove_conn(): remove iscsi_cls_conn from sysfs

Signed-off-by: Wenchao Hao <haowe...@huawei.com>
Signed-off-by: Wu Bo <wub...@huawei.com>
---

drivers/scsi/scsi_transport_iscsi.c | 97 +++++++++++++++++++++++++++++
include/scsi/scsi_transport_iscsi.h | 4 ++
2 files changed, 101 insertions(+)

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 554b6f784223..65117ed5626e 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2340,6 +2340,103 @@ void iscsi_free_session(struct iscsi_cls_session *session)

}
EXPORT_SYMBOL_GPL(iscsi_free_session);

+/**
+ * iscsi_alloc_conn - alloc iscsi class connection
+ * @session: iscsi cls session
+ * @dd_size: private driver data size
+ * @cid: connection id

+ return err;
+ }
+ err = transport_register_device(&conn->dev);
+ if (err) {
+ iscsi_cls_session_printk(KERN_ERR, session,
+ "could not register transport's dev\n");
+ device_del(&conn->dev);

+ return err;
+ }
+
+ spin_lock_irqsave(&connlock, flags);
+ list_add(&conn->conn_list, &connlist);
+ spin_unlock_irqrestore(&connlock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iscsi_add_conn);
+
+/**
+ * iscsi_remove_conn - remove iscsi class connection from sysfs

+ * @conn: iscsi cls connection
+ *

+ * this would remove iscsi_cls_conn from sysfs, and wait for previous
+ * read/write of iscsi_cls_conn's attributes in sysfs finishing
+ */
+void iscsi_remove_conn(struct iscsi_cls_conn *conn)
+{

+ unsigned long flags;
+

+ spin_lock_irqsave(&connlock, flags);
+ list_del(&conn->conn_list);
+ spin_unlock_irqrestore(&connlock, flags);
+
+ transport_unregister_device(&conn->dev);

+ device_del(&conn->dev);
+}
+EXPORT_SYMBOL_GPL(iscsi_remove_conn);

+
/**
* iscsi_create_conn - create iscsi class connection

* @session: iscsi cls session

diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index c5d7810fd792..ae686addde0c 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -441,6 +441,10 @@ extern struct iscsi_cls_session *iscsi_create_session(struct Scsi_Host *shost,

unsigned int target_id);
extern void iscsi_remove_session(struct iscsi_cls_session *session);
extern void iscsi_free_session(struct iscsi_cls_session *session);
+extern struct iscsi_cls_conn *iscsi_alloc_conn(struct iscsi_cls_session *sess,
+ int dd_size, uint32_t cid);
+extern int iscsi_add_conn(struct iscsi_cls_conn *conn);
+extern void iscsi_remove_conn(struct iscsi_cls_conn *conn);

extern struct iscsi_cls_conn *iscsi_create_conn(struct iscsi_cls_session *sess,
int dd_size, uint32_t cid);
extern void iscsi_put_conn(struct iscsi_cls_conn *conn);

--
2.32.0