linux-kernel - Re: [BUG][2.6.38] IRQ Lock Inversion / i915 fails

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <AANLkTi=ZSS=gDtGOcKBdE0BfJLpu0Ye1UhuNcbkz70Vs@mail.gmail.com>
Date:	Thu, 17 Mar 2011 10:33:04 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Knut Petersen <Knut_Petersen@...nline.de>,
	Jaroslav Kysela <perex@...ex.cz>,
	Chris Wilson <chris@...is-wilson.co.uk>,
	jesse.barnes@...el.com, gregkh@...e.de,
	linux-kernel@...r.kernel.org,
	David Müller <d.mueller@...oft.ch>
Subject: Re: [BUG][2.6.38] IRQ Lock Inversion / i915 fails

On Thu, Mar 17, 2011 at 10:15 AM, Takashi Iwai <tiwai@...e.de> wrote:
>
> The trigger callback should be called always in irq-disabled context,
> so this should be OK.

Oh, ok. I missed the snd_pcm_action_lock_irq() thing disabling
interrupts in that call sequence..

> But loopback_pos_update() is called in the
> timer callback, and this can be the issue.

Hmm. If the timer callback is the only other case doing that, then
that should be ok.

In fact, now that I look at that lockdep thing, I'm confused. Where
does the hard irq come in at all for that lock? It seems to come from
self_group.lock, but I don't see why/how they nest.

That said, the sound locking is odd, I'm sure you see it. But a
commentary about how this came about in the changelog would be good.

                     Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/