From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 0/6] Clean up the sdio_uart driver and fix the tty code Date: Tue, 03 Nov 2009 13:58:56 +0000 Message-ID: <4AF03720.5070506@csr.com> References: <20091102164039.11877.88825.stgit@localhost.localdomain> <20091102191604.010acbc9@lxorguk.ukuu.org.uk> <20091103120618.26b669be@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from cluster-d.mailcontrol.com ([85.115.60.190]:55038 "EHLO cluster-d.mailcontrol.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750838AbZKCOAE (ORCPT ); Tue, 3 Nov 2009 09:00:04 -0500 In-Reply-To: <20091103120618.26b669be@lxorguk.ukuu.org.uk> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Alan Cox Cc: Nicolas Pitre , Alan Cox , linux-mmc@vger.kernel.org, lkml , dhowells@redhat.com Alan Cox wrote: > > The claim method takes the mutex, checks if it is NULL and acts > accordingly but it releases the mutex, which makes it useless as the code > then uses port->func. If I move the release of the mutex to the > release_func method then that fixes almost all cases. > > The one I'm stuck on is this > > > CPU1 CPU2 > > > sdio_uart_irq > sdio_uart_port_remove > port->func = NULL; > sdio_in > BUG_ON This is actually happening? sdio_claim_host()/sdio_release_host() act like a mutex so sdio_uart_port_remove() will wait in sdio_claim_host() until sdio_uart_irq() returns (SDIO interrupt handlers are called with the host claimed). David -- David Vrabel, Senior Software Engineer, Drivers CSR, Churchill House, Cambridge Business Park, Tel: +44 (0)1223 692562 Cowley Road, Cambridge, CB4 0WZ http://www.csr.com/ Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom