hanging tasks - information about task state etc.

Thomas Doerfler Thomas.Doerfler at imd-systems.de
Sat Jan 25 20:57:21 UTC 2003

Hello Peter,

> Hash: SHA1
> Hi Joel, Thomas,
> thanks for your replies. dump_tasks finally helped me to find one problem.
> A task waiting for an event that gets usually sent from an irq. It turned
> out that the hardware triggering the irq hangs sometimes so that the irq
> is missing and my task waits forever.

Normally I know things the other way round: Software guys find 
"hardware errors" and later on the hardware guys find out that 
the hardware was not initialized/used properly by the 
software... :-)

> The other thing is not solved. Here I like to ask again for your advice..
> One of my tasks handles serial input. After my system runs for a while
> this task seems to get not scheduled anymore even if the system is not
> fully loaded. The task state is 8->STATES_DELAYING which means wait for
> timeout. This is ok because my old efi332 serial driver polls the rcv
> buffer to check if there is new data and waits for some ticks if nothing
> is there. Could it be possible that rtems_task_wake_after does not return
> for any reason?

Hm, the only reasons I could think of would be:

- Interrupts for System Tick do no longer occure, because: The 
interrupt is blocked, the timer has stopped or something 
similar. Can you check, whether the system tick still occures 
when your task hangs? You are working with a 68332 and BDM? 
Stop the system when your task hangs and set a breakpoint into 
the timer interrupt function. Does it get hit still?

- You call "rtems_task_wake_after" with a VERY long delay... 
(quite improbable)

maybe this helps a bit...

> Thanks,
> Peter
> > 
> > Peter, the gdb script I have posted a couple of times is a good start
> > on seeing what the tasks in the system are up to.  I would like to see
> > the gdb script eventually enhanced so that it could give you some
> > details
> > like decoding the task state into English and know that if in certain
> > states,
> > that Wait.id is what the task is waiting on.
> > 
> > > Thanks,
> > > Peter
> > > 
> Version: GnuPG v1.0.7 (GNU/Linux)
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