linux-kernel - [BUG?][NOMMU] microblaze: scheduling with interrupts disabled

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Message-Id: <1267761760.11837.7.camel@iscandar.digidescorp.com>
Date:	Thu, 04 Mar 2010 22:02:40 -0600
From:	"Steven J. Magnani" <steve@...idescorp.com>
To:	microblaze-uclinux@...e.uq.edu.au, monstr@...str.eu
Cc:	linux-kernel@...r.kernel.org
Subject: [BUG?][NOMMU] microblaze: scheduling with interrupts disabled

I ran across the following code in kernel/entry-nommu.S:

work_pending:
	andi	r11, r19, _TIF_NEED_RESCHED
	beqi	r11, 1f
	bralid	r15, schedule
	nop
1:	andi	r11, r19, _TIF_SIGPENDING
	beqi	r11, no_work_pending
	addk	r5, r1, r0
	addik	r7, r0, 1
	bralid	r15, do_signal
	addk	r6, r0, r0
	bri	no_work_pending

ENTRY(ret_to_user)
	disable_irq

	swi	r4, r1, PT_R4		/* return val */
	swi	r3, r1, PT_R3		/* return val */

	lwi	r6, r31, TS_THREAD_INFO /* get thread info */
	lwi	r19, r6, TI_FLAGS /* get flags in thread info */
	bnei	r19, work_pending
no_work_pending:
	disable_irq

If I am reading this correctly, it looks like schedule() and do_signal()
can get called with interrupts disabled. This looks like a bug to me. I
would propose to fix it by putting an enable_irq at work_pending.

Comments?
------------------------------------------------------------------------
 Steven J. Magnani               "I claim this network for MARS!
 www.digidescorp.com              Earthling, return my space modulator!"

 #include <standard.disclaimer>

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