From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Protection of critical section in PREEMPT_RT
Date: Mon, 4 Feb 2013 11:40:53 +0100 (CET)
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Cc: frank.rowand@am.sony.com, Stanislav Meduna <stano@meduna.org>,
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To: Jacky Lam <lamshuyin@gmail.com>
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Jacky,

On Mon, 4 Feb 2013, Jacky Lam wrote:

> Thanks.

Please stop top posting!
 
> I finally find that if I disable interrupt during ata_qc_issue() in
> libata-scsi.c, my sata driver works without any problem.

This is wrong. Which driver are you taling about ?
 
> But I find USB EHCI driver is more complicated. Kernel crashes every
> where when RT is turned on. It seems whenever the stack  spin_lock
> ehci->lock and interrupt comes at that moment, kernel will be crashes.
> The reason is EHCI interrupt handler will also take the same lock. If
> my point of view, USB stack seems no PREEMPT_RT safe. Is it correct?
> Am I miss anything?

Probably. First of all you don't tell us which driver you are
using. And w/o seing the code and the output of the kernel crash, we
can't help you at all.

Thanks,

	tglx