Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756805Ab2EYKqm (ORCPT ); Fri, 25 May 2012 06:46:42 -0400 Received: from mga11.intel.com ([192.55.52.93]:26785 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755273Ab2EYKql (ORCPT ); Fri, 25 May 2012 06:46:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="171254787" Date: Fri, 25 May 2012 12:02:16 +0100 From: Alan Cox To: Sasha Levin Cc: Ming Lei , Steven Rostedt , Alan Cox , Dave Jones , Linux Kernel , Greg Kroah-Hartman Subject: Re: 3.4+ tty lockdep trace Message-ID: <20120525120216.45381ec6@bob.linux.org.uk> In-Reply-To: References: <20120523002645.GA3490@redhat.com> <20120524121056.24fbdcdb@pyramind.ukuu.org.uk> <20120524155457.56e37df2@bob.linux.org.uk> <20120525023222.GC30024@home.goodmis.org> Organization: Intel X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Organisation: Intel Corporation UK Ltd, registered no. 1134945 (England), Registered office Pipers Way, Swindon, SN3 1RJ Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 942 Lines: 37 > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/