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From: Thomas Gleixner <tglx@linutronix.de>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	"Paul E. McKenney" <paulmck@us.ibm.com>,
	dipankar@in.ibm.com, shemminger@osdl.org,
	Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
	rusty@au1.ibm.com, tgall@us.ibm.com, jim.houston@comcast.net,
	gh@us.ibm.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Real-Time Preemption and RCU
Date: Sun, 20 Mar 2005 10:25:36 +0100	[thread overview]
Message-ID: <1111310736.17944.24.camel@tglx.tec.linutronix.de> (raw)
In-Reply-To: <423D19FE.7020902@colorfullife.com>

On Sun, 2005-03-20 at 07:36 +0100, Manfred Spraul wrote:
> cpu 1:
> acquire random networking spin_lock_bh()
> 
> cpu 2:
> read_lock(&tasklist_lock) from process context
> interrupt. softirq. within softirq: try to acquire the networking lock.
> * spins.
> 
> cpu 1:
> hardware interrupt
> within hw interrupt: signal delivery. tries to acquire tasklist_lock.
> 
> --> deadlock.

Signal delivery from hw interrupt context (interrupt is flagged
SA_NODELAY) is not possible in RT preemption mode. The
local_irq_save_nort() check in __cache_alloc will catch you.

When it happens from a threaded irq handler the situation is solvable by
the PI code.

tglx



  reply	other threads:[~2005-03-20  9:25 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-18  0:20 Real-Time Preemption and RCU Paul E. McKenney
2005-03-18  7:49 ` Ingo Molnar
2005-03-18 16:43   ` Paul E. McKenney
2005-03-18 17:11     ` Ingo Molnar
2005-03-18 17:29       ` Paul E. McKenney
2005-03-18 20:35       ` Paul E. McKenney
2005-03-18 22:22         ` Paul E. McKenney
2005-03-19  0:48           ` Paul E. McKenney
2005-03-18  8:44 ` Ingo Molnar
2005-03-18  9:04 ` Ingo Molnar
2005-03-18  9:38   ` Ingo Molnar
2005-03-18  9:13 ` Ingo Molnar
2005-03-18  9:28   ` Ingo Molnar
2005-03-18  9:53     ` Ingo Molnar
2005-03-18 15:33       ` Paul E. McKenney
2005-03-19  5:03     ` Manfred Spraul
2005-03-19 16:26       ` Ingo Molnar
2005-03-20  6:36         ` Manfred Spraul
2005-03-20  9:25           ` Thomas Gleixner [this message]
2005-03-20 16:57             ` Manfred Spraul
2005-03-20 21:38               ` Bill Huey
2005-03-20 21:59                 ` Bill Huey
2005-03-18 10:03 ` Ingo Molnar
2005-03-18 11:30   ` Ingo Molnar
2005-03-18 16:48     ` Esben Nielsen
2005-03-18 17:19       ` Ingo Molnar
2005-03-20 13:29         ` Esben Nielsen
2005-03-20 22:38           ` Paul E. McKenney
2005-03-20 23:23             ` Esben Nielsen
2005-03-22  5:53               ` Paul E. McKenney
2005-03-22  8:55                 ` Esben Nielsen
2005-03-22  9:20                   ` Ingo Molnar
2005-03-22 10:19                     ` Esben Nielsen
2005-03-23  5:40                   ` Paul E. McKenney
2005-03-23 11:44                     ` Esben Nielsen
2005-03-24  7:02                       ` Paul E. McKenney
2005-03-22 10:56           ` Ingo Molnar
2005-03-22 11:39             ` Esben Nielsen
2005-03-22 13:10               ` Ingo Molnar
2005-03-22 15:08                 ` Esben Nielsen
2005-03-18 15:48   ` Paul E. McKenney
2005-03-18 11:38 ` Ingo Molnar
2005-03-18 12:56 ` Bill Huey
2005-03-18 13:17   ` Bill Huey
2005-03-18 15:57     ` Paul E. McKenney
2005-03-18 16:02     ` Ingo Molnar
2005-03-18 16:55       ` Esben Nielsen
2005-03-22 10:04         ` Bill Huey
2005-03-22 10:17           ` Bill Huey
2005-03-22 10:34             ` Bill Huey
2005-03-22 10:38           ` Esben Nielsen
2005-03-18 22:26       ` Herbert Xu
2005-03-19 16:31         ` Ingo Molnar
2005-03-20  8:01           ` Kyle Moffett
2005-03-22  8:08             ` Ingo Molnar
2005-03-18 15:54   ` Paul E. McKenney
2005-03-18 15:58     ` Ingo Molnar
2009-06-11 22:57 real-time preemption " James Huang

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