[Xorp-hackers] rtrmgr crash on SIGABRT because of pop_front in task_done

[Li Zhao]

I have three cases in which this crash occured. The one you set up is one of them.
I used you fix. It did prevent rtrmgr from crashing in all three cases. That is good.
But i am afraid that is not the root cause because task manager always check if the tasklist
is not empty before it run any task.
I will keep debugging to look for the root cause and will let you know if
I found anything.

Thank you for spending time on this.

Li

--- On Thu, 10/29/09, Ben Greear <greearb at candelatech.com> wrote:

> From: Ben Greear <greearb at candelatech.com>
> Subject: Re: [Xorp-hackers] rtrmgr crash on SIGABRT because of pop_front in task_done
> To: "Li Zhao" <lizhaous2000 at yahoo.com>
> Cc: xorp-hackers at icir.org
> Date: Thursday, October 29, 2009, 11:24 PM
> Li Zhao wrote:
> > I added a new protocol and I can start it in CLI by
> command "create protocol XXX", but the rtrmgr crashed after
> command "delete protocol XXX".
> > I can also easily reproduce the exactlt same crash via
> the following steps:
> > 
> > 0. I am running xorp processes on an embedded system.
> > 1. start rtrmgr from linux shell on the system;
> > 2. manually start xorp_static_routes from linux shell.
> This static will hijack the xrl channels to rtrmgr;
> > 3. use cli command "create protocol static" to start a
> second xorp_static_routes.
> > 4. use cli command "delete protocol static" to stop
> static. both xorp_static_routes were terminated. depended
> process like fea, rib and policy were also terminated.
> rtrmgr crash.
> >   
> Ok, the crash is because if you do a pop_front() on an
> empty list, it's going to crash.
> 
> I'm not sure why the list is empty here.  Seems to
> indicate task-manager logic is busted
> with regard to task list management and/or callbacks are
> being called against a wrong
> task-manager.
> 
> Do you actually need to do this operation for your
> project?  If so, you probably will want
> to investigate task-manager logic in detail to figure out
> why this is happening.
> 
> The attached patch fixes the crash, but the underlying bug
> persists.  Most of the patch is debugging
> code, but I'm leaving it in my tree because it will help
> next time we hit a similar problem.
> 
> Thanks,
> Ben
> 
> -- Ben Greear <greearb at candelatech.com>
> Candela Technologies Inc  http://www.candelatech.com
> 
> 
> 
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