Messages in this thread | | | Date | Wed, 2 Jun 2010 09:19:21 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: Long playing threaded interrupt handlers |
| |
On Wed, 2 Jun 2010, Dmitry Torokhov wrote:
> HI Thomas, > > The threaded IRQ infrastructure that went into the kernel is extremely > helpful, however in the input land there are quite a few devices that > require polling after an IRQ has been raised. > > Currently most such drivers, instead of threaded interrupts, still use > [delayed] work to do the polling, and still face the issue of shutting > down interrupt and scheduled work in a raceless way leaving irq enable > counter balanced. Is it allowed to have threaded ISR execute for > extended a amount of time, and do the required polling, provided that > ISR does certain checks to finish promply in case when we unbind the > driver or try to suspend the device?
Sure, why not ? The only thing we need to think about is when the poll is busy polling for a long time, then we need to lower the irq thread priority to SCHED_OTHER in order not to hog the CPU.
Vs. shutdown: The thread handler needs to be aware of a shutdown request in it's poll loop, so something like this should work:
handler() { while (work_to_do() && !shutdown) { ..... } }
unbind() { shutdown = 1; free_irq(); }
Thanks,
tglx
| |