iscsi warning in 2.6.33-rc2

iscsi warning in 2.6.33-rc2

[Tao Ma]

Hi all,
	I met with this warning when using iscsi with the 2.6.33-rc2.

------------[ cut here ]------------
WARNING: at drivers/scsi/libiscsi_tcp.c:996 
iscsi_tcp_task_xmit+0x15e/0x2b8 [libiscsi_tcp]()
Hardware name: OptiPlex 745
unexpected fifo state
Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables 
x_tables bridge stp netconsole autofs4 hidp rfcomm l2cap crc16 bluetooth 
rfkill ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager 
ocfs2_stackglue configfs sunrpc ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad 
ib_core ib_addr ipv6 iscsi_tcp libiscsi_tcp libiscsi 
scsi_transport_iscsi dm_mirror dm_region_hash dm_log dm_multipath dm_mod 
video output sbs sbshc battery acpi_memhotplug ac lp sg 
snd_hda_codec_analog snd_hda_intel dcdbas rtc_cmos tg3 snd_hda_codec 
rtc_core parport_pc rtc_lib libphy sr_mod cdrom parport tpm_tis 
serio_raw snd_seq_dummy tpm tpm_bios snd_seq_oss snd_seq_midi_event 
button snd_seq e1000 snd_seq_device shpchp snd_pcm_oss snd_mixer_oss 
i2c_i801 i2c_core snd_pcm snd_timer snd soundcore snd_page_alloc pcspkr 
ata_piix libata sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci_hcd 
[last unloaded: microcode]
Pid: 4125, comm: iscsi_q_4 Not tainted 2.6.33-rc2 #1
Call Trace:
  [<ffffffffa028a34c>] ? iscsi_xmitworker+0x0/0x2ae [libiscsi]
  [<ffffffffa029ae77>] ? iscsi_tcp_task_xmit+0x15e/0x2b8 [libiscsi_tcp]
  [<ffffffff8203712f>] ? warn_slowpath_common+0x77/0x8e
  [<ffffffff820371a2>] ? warn_slowpath_fmt+0x51/0x59
  [<ffffffff822f3ba0>] ? _raw_spin_lock_bh+0x9/0x1f
  [<ffffffffa029ae77>] ? iscsi_tcp_task_xmit+0x15e/0x2b8 [libiscsi_tcp]
  [<ffffffffa028a34c>] ? iscsi_xmitworker+0x0/0x2ae [libiscsi]
  [<ffffffffa028984f>] ? iscsi_xmit_task+0x45/0x83 [libiscsi]
  [<ffffffffa028a4d9>] ? iscsi_xmitworker+0x18d/0x2ae [libiscsi]
  [<ffffffff8204be27>] ? worker_thread+0x146/0x1e0
  [<ffffffff8204e79b>] ? autoremove_wake_function+0x0/0x2e
  [<ffffffff8204bce1>] ? worker_thread+0x0/0x1e0
  [<ffffffff8204e4a7>] ? kthread+0x79/0x81
  [<ffffffff82003614>] ? kernel_thread_helper+0x4/0x10
  [<ffffffff8204e42e>] ? kthread+0x0/0x81
  [<ffffffff82003610>] ? kernel_thread_helper+0x0/0x10
---[ end trace 962db674bc379fa3 ]---

http://pastebin.com/m62a71466

iscsi target is
[root@ocfs2-test1 ~]# cat /etc/distro-release
Openfiler NSA 2.3

iscsi initiator is
[root@ocfs2-test2 ~]# rpm -qa|grep iscsi
iscsi-initiator-utils-6.2.0.868-0.18.el5

The other thing I can confirm is that I didn't meet with such problem in 
2.6.32-rc8.

Regards,
Tao

Re: iscsi warning in 2.6.33-rc2

[Mike Christie]

[-- Attachment #1: Type: text/plain, Size: 776 bytes --]

On 12/29/2009 11:43 PM, Tao Ma wrote:
> Hi all,
> 	I met with this warning when using iscsi with the 2.6.33-rc2.
>
> ------------[ cut here ]------------
> WARNING: at drivers/scsi/libiscsi_tcp.c:996

....

>
> The other thing I can confirm is that I didn't meet with such problem in
> 2.6.32-rc8.
>

Sorry for the late reply. I am just getting back.

I think this is due to the kfifo changes that got merged recently.

For the iscsi side if there is nothing in the r2tqueue fifo at this time 
it is fine. It just means that there is nothing to process, so I think 
that the warn on should just not have been added.

Could you try the attached patch? I have only compile tested it. I am 
starting up some testing for the patch and the other fifo changes that 
got merged now.

[-- Attachment #2: iscsi-do-not-warn-on-empty-r2t.patch --]
[-- Type: text/x-patch, Size: 790 bytes --]

An empty r2tqueue is a valid state. It just means that we have
processed all that there was to do.

This patch removes the WARN_ON.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>

diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index db6856c..4ad87fd 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -992,12 +992,10 @@ static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 		if (r2t == NULL) {
 			if (kfifo_out(&tcp_task->r2tqueue,
 			    (void *)&tcp_task->r2t, sizeof(void *)) !=
-			    sizeof(void *)) {
-				WARN_ONCE(1, "unexpected fifo state");
+			    sizeof(void *))
 				r2t = NULL;
-			}
-
-			r2t = tcp_task->r2t;
+			else
+				r2t = tcp_task->r2t;
 		}
 		spin_unlock_bh(&session->lock);
 	}

Re: iscsi warning in 2.6.33-rc2

[Tao Ma]

It works. Thanks.

Tested-by: Tao Ma <tao.ma@oracle.com>

Mike Christie wrote:
> On 12/29/2009 11:43 PM, Tao Ma wrote:
>> Hi all,
>>     I met with this warning when using iscsi with the 2.6.33-rc2.
>>
>> ------------[ cut here ]------------
>> WARNING: at drivers/scsi/libiscsi_tcp.c:996
> 
> ....
> 
>>
>> The other thing I can confirm is that I didn't meet with such problem in
>> 2.6.32-rc8.
>>
> 
> Sorry for the late reply. I am just getting back.
> 
> I think this is due to the kfifo changes that got merged recently.
> 
> For the iscsi side if there is nothing in the r2tqueue fifo at this time 
> it is fine. It just means that there is nothing to process, so I think 
> that the warn on should just not have been added.
> 
> Could you try the attached patch? I have only compile tested it. I am 
> starting up some testing for the patch and the other fifo changes that 
> got merged now.
>