[Stgt-devel] [PATCH 1/1] list.h: prevent a SEGV if we try to clear a list that is already empty

[ronnie sahlberg]

Ok.

I easily reproduced it with three hosts.

One target:
One host runs tgtd and exports a LUN.
Attach GDB to tgtd.


Two initiators:
The two other hosts run iscsi initiator to log into the target.
I ran a small : while true; do dd if=... of=/dev/null bs=512 count=1;
date; done   on each one of them to see that they were doing i/o
continously.


On one of the initiators, disable all the respose traffic coming back
from the target
iptables -I INPUT -s <target IP> -p tcp --sport 3260 -j DROP

The output from the while/dd loop on that initiator would immediately hang.
After a while tgtd would SEGV.



ronnie


On Wed, Jul 9, 2008 at 3:32 PM, FUJITA Tomonori
<fujita.tomonori at lab.ntt.co.jp> wrote:
> On Mon, 7 Jul 2008 11:12:08 +1000
> "ronnie sahlberg" <ronniesahlberg at gmail.com> wrote:
>
>> Please apply.
>>
>> I have reproduced the SEGV that was reported when I/O has failed/been aborted.
>> This pathc prevents the SEGV from occuring in this situation.
>>
>> It does however not address the root cause why tgtd tries to clear a
>> list that is already (and it should know is already?) empty.
>
> It might be easy to debug tgtd with this workaround patch but after
> all we need to fix the root problem. It's likely that this workaround
> will hurt us in the future.
>
> I think that there might be bugs in Task Management Message
> handling. I try to reproduce the problem after I get the detailed
> information of Tomasz's configuration.
>