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Date: Wed, 9 Mar 2022 19:01:12 +0800
From: Wenchao Hao <haowenchao@...wei.com>
To: Mike Christie <michael.christie@...cle.com>,
Lee Duncan <lduncan@...e.com>, Chris Leech <cleech@...hat.com>,
"James E . J . Bottomley" <jejb@...ux.ibm.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
<open-iscsi@...glegroups.com>, <linux-scsi@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: Wu Bo <wubo40@...wei.com>, Zhiqiang Liu <liuzhiqiang26@...wei.com>,
<linfeilong@...wei.com>
Subject: Re: [PATCH v2 1/3] scsi: iscsi: Add helper functions to manage
iscsi_cls_conn
On 2022/3/9 1:19, Mike Christie wrote:
> On 3/8/22 9:09 PM, Wenchao Hao wrote:
>> 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 <haowenchao@...wei.com>
>> Signed-off-by: Wu Bo <wubo40@...wei.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.
>
> 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.
>
>
>> + */
>> +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);
>
> I would call iscsi_free_conn. instead of put_device.
>
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.
> 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.
>
>
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