Re: [PATCH 4/4] bnx2i: Add bnx2i iSCSI driver.

On Tue, 2009-05-19 at 07:22 -0700, Mike Christie wrote:

Michael Chan wrote:

quoted

Here are the more generic NETLINK_ISCSI messages and the iscsi transport
code to support them, please review.

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index d69a53a..60cb6cb 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c

@@ -995,6 +995,39 @@ int iscsi_recv_pdu(struct iscsi_cls_conn *conn, struct iscsi_hdr *hdr,
 }
 EXPORT_SYMBOL_GPL(iscsi_recv_pdu);
 
+int iscsi_offload_mesg(struct Scsi_Host *shost,
+		       struct iscsi_transport *transport, uint32_t type,
+		       char *data, uint16_t data_size)
+{
+	struct nlmsghdr	*nlh;
+	struct sk_buff *skb;
+	struct iscsi_uevent *ev;
+	int len = NLMSG_SPACE(sizeof(*ev) + data_size);
+
+	skb = alloc_skb(len, GFP_ATOMIC);
+	if (!skb) {
+		printk(KERN_ERR "can not deliver iscsi offload message:OOM\n");
+		return -ENOMEM;
+	}
+
+	nlh = __nlmsg_put(skb, 0, 0, 0, (len - sizeof(*nlh)), 0);
+	ev = NLMSG_DATA(nlh);
+	memset(ev, 0, sizeof(*ev));
+	ev->type = type;
+	ev->transport_handle = iscsi_handle(transport);
+	switch (type) {
+	case ISCSI_KEVENT_PATH_REQ:
+		ev->r.req_path.host_no = shost->host_no;
+	case ISCSI_KEVENT_IF_DOWN:
+		ev->r.notify_if_down.host_no = shost->host_no;
+	}
+
+	memcpy((char*)ev + sizeof(*ev), data, data_size);
+
+	return iscsi_broadcast_skb(skb, GFP_KERNEL);

You can sync up what the gfp flag used here and for the alloc_skb call 
above. If you have process context, you probably want to use GFP_NOIO, 
because this could be called for reconnect for a disk in use.

If you do not have process context then you would need to use GFP_ATOMIC.

We have process context, but I think we should make it more general for
other future drivers and use GFP_ATOMIC.

quoted

+}
+EXPORT_SYMBOL_GPL(iscsi_offload_mesg);
+
 void iscsi_conn_error_event(struct iscsi_cls_conn *conn, enum iscsi_err error)
 {
 	struct nlmsghdr	*nlh;

@@ -1393,6 +1426,30 @@ iscsi_set_host_param(struct iscsi_transport *transport,
 }
 
 static int
+iscsi_set_path(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+{
+	struct Scsi_Host *shost;
+	struct iscsi_path *params;
+	int err;
+
+	if (!transport->set_path)
+		return -ENOSYS;
+
+	shost = scsi_host_lookup(ev->u.set_path.host_no);
+	if (!shost) {
+		printk(KERN_ERR "set path could not find host no %u\n",
+		       ev->u.set_path.host_no);
+		return -ENODEV;
+	}
+
+	params = (struct iscsi_path *)((char*)ev + sizeof(*ev));
+	err = transport->set_path(shost, params);
+				      
+	scsi_host_put(shost);
+	return err;
+}
+
+static int
 iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	int err = 0;

@@ -1411,7 +1468,8 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	if (!try_module_get(transport->owner))
 		return -EINVAL;
 
-	priv->daemon_pid = NETLINK_CREDS(skb)->pid;
+	if (nlh->nlmsg_type != ISCSI_UEVENT_PATH_UPDATE)
+		priv->daemon_pid = NETLINK_CREDS(skb)->pid;
 

Instead of using broadcast above and in some other places and then doing 
this check, could we just use multicast groups or something else? The 
events from iscsid could be in one group and then events for uip would 
be in another?

We need to do this check because we don't want the daemon_pid to be
overwritten with a pid that is not iscsid's.  If it was overwritten,
unicast NETLINK_ISCSI messages will not reach iscsid.

We can use multicast group 2 for the new messages if you prefer.  This
way, I think iscsid will not receive the new messages since it is only
listening on group 1.  The pid check will still be needed though.

Or is it more common to do it like this or will it break compat with 
other tools if we change it?