From: Bob Copeland <me@bobcopeland.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Christian Lamparter <chunkeey@googlemail.com>,
wireless <linux-wireless@vger.kernel.org>
Subject: Re: Locking problem reported for mainline
Date: Tue, 11 Jan 2011 14:45:04 -0500 [thread overview]
Message-ID: <AANLkTikPoEjHRXjqVkSopCjUcyp7AauvFAfaVN_8T0qG@mail.gmail.com> (raw)
In-Reply-To: <4D2C85FE.4030709@lwfinger.net>
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.
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.
--
Bob Copeland %% www.bobcopeland.com
next prev parent reply other threads:[~2011-01-11 19:45 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 [this message]
2011-01-11 20:52 ` Larry Finger
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