Re: LIO Target behavior when Data-out PDU with DataSegmentLength = 0

["Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>]

Hi Santosh,

On Wed, 2013-11-06 at 11:50 +0530, santosh kulkarni wrote:
> Hi,
> 
> I am currently working on developing a iSCSI protocol conformance suite. 
> I am currently testing it against a  LIO based target.
> The LIO target details are as follows
> kernel : 3.10.13-101.fc18.x86_64 #1 SMP(Fedora 18)
> rpm -qa | grep target
> scsi-target-utils-1.0.38-1.fc18.x86_64
> selinux-policy-targeted-3.11.1-66.fc18.noarch
> targetcli-2.1.fb30-1.fc18.noarch
> I am facing few issues and needed to clarify few of my doubts.
> 1. Our suite currently checks the behavior of a target when a Data-Out 
> PDU with  DataSegmentLength set to 0 is sent out. And what i see in the 
> target is as follows
> 
> ~# dmesg
> [599509.602032] DataOUT payload is ZERO, protocol error.
> [599675.065060] DataOUT payload is ZERO, protocol error.
> 
> But the RFC states the following
> 
> 
> 
> 10.7.7.  DataSegmentLength
> This is the data payload length of a SCSI Data-In or SCSI Data-Out PDU. 
> "The sending of 0 length data segments should be avoided, but initiators 
> and targets MUST be able to properly receive 0 length data
> 
>     segments."
> Is this the default behavior of LIO. It would be great if someone could 
> clarify my doubts.
> 

Here is a quick patch to drop the sending of the REJECT, and ignore zero
length ISCSI_OP_SCSI_DATA_OUTs.

Care to test..?

--nab

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index e183352..ab64cbb 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1249,9 +1249,8 @@ iscsit_check_dataout_hdr(struct iscsi_conn *conn, unsigned char *buf,
        int rc;
 
        if (!payload_length) {
-               pr_err("DataOUT payload is ZERO, protocol error.\n");
-               return iscsit_add_reject(conn, ISCSI_REASON_PROTOCOL_ERROR,
-                                        buf);
+               pr_warn("DataOUT payload is ZERO, ignoring.\n");
+               return 0;
        }
 
        /* iSCSI write */
@@ -1481,7 +1480,7 @@ EXPORT_SYMBOL(iscsit_check_dataout_payload);
 
 static int iscsit_handle_data_out(struct iscsi_conn *conn, unsigned char *buf)
 {
-       struct iscsi_cmd *cmd;
+       struct iscsi_cmd *cmd = NULL;
        struct iscsi_data *hdr = (struct iscsi_data *)buf;
        int rc;
        bool data_crc_failed = false;


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