Re: Linux 2.6.16-rc3

Matthew Wilcox
2006-02-18T05:30:32Z

On Fri, Feb 17, 2006 at 06:12:04PM -0800, Roland Dreier wrote:
> > +int execute_in_process_context(void (*fn)(void *data), void *data,
> > + struct execute_work *ew)
> > +{
> > + if (!in_interrupt()) {
> > + fn(data);
> > + return 0;
> > + }
>
> Is testing in_interrupt() really sufficient to make this work? I seem
> to remember that (at least) with CONFIG_PREEMPT disabled, there are
> contexts where it is not safe to sleep but where both in_interrupt()
> and in_atomic() still return 0.

That's correct -- in process context, with PREEMPT disabled and a spinlock
held, it's unsafe to call this function. It works well for the SCSI
usage (where it's called either in interrupt context or in user
context with no spinlocks held), but it's not *always* safe.

I think this needs to be documented in the kerneldoc.

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