Re: calling schedule() from interupt context

[Robert Love <rml@tech9.net>]

On Fri, 2002-11-22 at 03:54, dan carpenter wrote:

(Next time trim your CC list: none of those poor guys needed this
email..)

> In drivers/net/tokenring/3c359.c xl_interrupt() calls schedule().
> The path from xl_interupt to schedule is:
> xl_rx ==> netif_rx ==> 
> kfree_skb ==> __kfree_skb ==> 
> secpath_put ==> __secpath_destroy ==> 
> xfrm_state_put ==> __xfrm_state_destroy ==> xfrm_put_type ==> 
> module_put ==> put_cpu ==> preempt_schedule ==> schedule

Are you actually seeing this code path or is this just what your script
is showing you?

preempt_schedule() will not call schedule() if the preempt_count is
non-zero.  Inside an interrupt handler, it is always at least one.  So
nothing will drop it to zero, and we will never preempt.

> The third thing I was wondering is:  xl_interupt is holding a 
> spin_lock(&xl_priv->xl_lock).   I know that you're not supposed to call shedule()
> while holding a spin lock, but is it ok to call preempt_schedule()?

Same as above.  preempt_schedule() only calls schedule when
preempt_count is zero.  It is not if you hold a lock, and it is not
inside an interrupt handler.

	Robert Love