linux-kernel - Re: 3.4+ tty lockdep trace

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] [day] [month] [year] [list]

Date:	Fri, 25 May 2012 12:02:16 +0100
From:	Alan Cox <alan@...ux.intel.com>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	Ming Lei <tom.leiming@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: 3.4+ tty lockdep trace

> Applying Ming's patch over Alan's 2 patches from yesterday, I'm still
> seeing two lockdep warnings. Full trace attached.

In that code path we've just succesfully done

	tty_lock_pair(tty, o_tty)

(no warning issued)

We've then called into tty_ldisc_release which has done

	tty_unlock_pair(tty, o_tty);

and then

	tty_lock_pair(tty, o_tty);

which can't error unless our locking hosed

and at that point we then then do a recursive

	tty_ldisc_release(o_tty, NULL)

which embarrassingly already has a comment above it I put there saying


        /* This will need doing differently if we need to lock */


Let me go rewrite that particular routine to make sense with the
locking in place.

--
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/