Re: queue_work from interrupt Real time preemption2.6.11-rc2-RT-V0.7.37-03

[Mark Gross <mgross@linux.intel.com>]

On Monday 14 February 2005 13:24, Steven Rostedt wrote:
> On Mon, 2005-02-14 at 12:40 -0800, Mark Gross wrote:
> > I'm working on a tweak to the preepmtive soft IRQ implementation using
> > work queues and I'm having problems with a BUG assert when trying to
> > queue_work.
> >
> > Souldn't I be able to call queue_work form ISR context?
>
> Yes, but not with interrupts disabled.
>

Hmm.  It seems to me that one should be able to call queue_work from wherever 
you can call raise_softirq.  This constraint adds a bit of asymetry in the 
deffered processing API's


> > --mgross
> >
> > ---------------------------
> >
> > | preempt count: 00000001 ]
> > | 1-level deep critical section nesting:
> >
> > ----------------------------------------
> > .. [<c0140f5d>] .... print_traces+0x1d/0x60
> > .....[<c01042a3>] ..   ( <= dump_stack+0x23/0x30)
> >
> > BUG: sleeping function called from invalid context IRQ 20(2039) at
> > kernel/rt.c in_atomic():0 [00000000], irqs_disabled():1
>
> Here you have interrupts disabled. Since you are tweaking the softirq I
> don't know your code, but the kernel should not schedule after turning
> off interrupts, and the spinlocks under the PREEMPT kernel, may now
> sleep (unless they are raw_spin_locks).  Here we also see that
> queue_work calls spin_lock_irqsave.  I'm suspecting that you turned off
> interrupts somewhere.
>
> -- Steve

I'll post my code soon, I hope.  I now need to work around this API problem :(

thanks, 

--mgross