From: Larry Finger <Larry.Finger@lwfinger.net>
To: Bob Copeland <me@bobcopeland.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>,
wireless <linux-wireless@vger.kernel.org>
Subject: Re: Locking problem reported for mainline
Date: Tue, 11 Jan 2011 14:52:32 -0600 [thread overview]
Message-ID: <4D2CC310.5060003@lwfinger.net> (raw)
In-Reply-To: <AANLkTikPoEjHRXjqVkSopCjUcyp7AauvFAfaVN_8T0qG@mail.gmail.com>
On 01/11/2011 01:45 PM, Bob Copeland wrote:
> On Tue, Jan 11, 2011 at 11:31 AM, Larry Finger
> <Larry.Finger@lwfinger.net> wrote:
>> Is there a document that explains what the meaning of these semantics?
>>
>> inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
>> kdostartupconfi/3502 [HC1[1]:SC0[0]:HE0:SE1] takes:
>> (&(&list->lock)->rlock#5){?.-...}, at: [<ffffffff812995c6>]
>> skb_queue_tail+0x26/0x60
>> {HARDIRQ-ON-W} state was registered at:
>
> I'm not sure about all the HC1[1]:SC0[0] etc stuff, but check out
> Documentation/lockdep-design.txt for the basics.
That one I had read.
> In this case, someone took a lock with interrupts enabled (HARDIRQ-ON-W)
> while someone else took it in a hard IRQ context (IN-HARDIRQ-W) where
> they are normally disabled. The problem of course is:
>
> cpu0:
> spin_lock(&foo);
> do some stuff protected by foo;
>
> ----> interrupt happens here
> spin_lock(&foo); /* darn, deadlock! */
> other stuff;
> spin_unlock(&foo);
> <----
>
> spin_unlock(&foo);
>
> Could be a missing _irqsave() if it's not, as Stanislaw suggested, a false
> positive.
I suspected the message meant mixed interrupts disabled/enabled, but thanks for
the confirmation.
Thanks,
Larry
prev parent reply other threads:[~2011-01-11 20:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-10 5:03 Locking problem reported for mainline Larry Finger
2011-01-10 16:06 ` Stanislaw Gruszka
2011-01-10 18:13 ` Christian Lamparter
2011-01-10 19:11 ` Larry Finger
2011-01-10 19:18 ` Christian Lamparter
2011-01-11 16:31 ` Larry Finger
2011-01-11 19:45 ` Bob Copeland
2011-01-11 20:52 ` Larry Finger [this message]
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