From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752684AbXCIRcV (ORCPT ); Fri, 9 Mar 2007 12:32:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752692AbXCIRcV (ORCPT ); Fri, 9 Mar 2007 12:32:21 -0500 Received: from out-smtp.licor.com ([63.151.144.205]:2581 "HELO out-smtp.licor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752684AbXCIRcU (ORCPT ); Fri, 9 Mar 2007 12:32:20 -0500 Message-ID: <45F19A20.5010700@licor.com> Date: Fri, 09 Mar 2007 11:32:16 -0600 From: Chris Lesiak User-Agent: Thunderbird 1.5.0.9 (X11/20070212) MIME-Version: 1.0 To: David Brownell CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH] spi subsystem: destroy the spi_bitbang workqueue only after the spi master is unregistered References: <45EEE34A.6070009@licor.com> <200703071031.39997.david-b@pacbell.net> <45EF4F32.2050601@licor.com> <200703082219.33296.david-b@pacbell.net> In-Reply-To: <200703082219.33296.david-b@pacbell.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Chris Lesiak This patch fixes a bug in the cleanup of an spi_bitbang bus. The workqueue associated with the bus was destroyed before the call to spi_unregister_master. That meant that spi devices on that bus would be unable to do IO in their remove method. The shutdown flag should have been able to prevent a segfault, but was never getting set. By waiting to destroy the workqueue until after the master is unregistered, devices are able to do IO in their remove methods. An added benefit is that neither the shutdown flag nor a wait for the queue of messages to empty is needed. Signed-off-by: Chris Lesiak --- diff -uprN -X linux-2.6.20-vanilla/Documentation/dontdiff linux-2.6.20-vanilla/drivers/spi/spi_bitbang.c linux-2.6.20/drivers/spi/spi_bitbang.c --- linux-2.6.20-vanilla/drivers/spi/spi_bitbang.c 2007-02-04 12:44:54.000000000 -0600 +++ linux-2.6.20/drivers/spi/spi_bitbang.c 2007-03-09 11:23:42.000000000 -0600 @@ -302,10 +302,6 @@ static void bitbang_work(struct work_str setup_transfer = NULL; list_for_each_entry (t, &m->transfers, transfer_list) { - if (bitbang->shutdown) { - status = -ESHUTDOWN; - break; - } /* override or restore speed and wordsize */ if (t->speed_hz || t->bits_per_word) { @@ -410,8 +406,6 @@ int spi_bitbang_transfer(struct spi_devi m->status = -EINPROGRESS; bitbang = spi_master_get_devdata(spi->master); - if (bitbang->shutdown) - return -ESHUTDOWN; spin_lock_irqsave(&bitbang->lock, flags); if (!spi->max_speed_hz) @@ -506,28 +500,12 @@ EXPORT_SYMBOL_GPL(spi_bitbang_start); */ int spi_bitbang_stop(struct spi_bitbang *bitbang) { - unsigned limit = 500; - - spin_lock_irq(&bitbang->lock); - bitbang->shutdown = 0; - while (!list_empty(&bitbang->queue) && limit--) { - spin_unlock_irq(&bitbang->lock); + spi_unregister_master(bitbang->master); - dev_dbg(bitbang->master->cdev.dev, "wait for queue\n"); - msleep(10); - - spin_lock_irq(&bitbang->lock); - } - spin_unlock_irq(&bitbang->lock); - if (!list_empty(&bitbang->queue)) { - dev_err(bitbang->master->cdev.dev, "queue didn't empty\n"); - return -EBUSY; - } + WARN_ON(!list_empty(&bitbang->queue)); destroy_workqueue(bitbang->workqueue); - spi_unregister_master(bitbang->master); - return 0; } EXPORT_SYMBOL_GPL(spi_bitbang_stop); diff -uprN -X linux-2.6.20-vanilla/Documentation/dontdiff linux-2.6.20-vanilla/include/linux/spi/spi_bitbang.h linux-2.6.20/include/linux/spi/spi_bitbang.h --- linux-2.6.20-vanilla/include/linux/spi/spi_bitbang.h 2007-02-04 12:44:54.000000000 -0600 +++ linux-2.6.20/include/linux/spi/spi_bitbang.h 2007-03-09 11:23:42.000000000 -0600 @@ -25,7 +25,6 @@ struct spi_bitbang { spinlock_t lock; struct list_head queue; u8 busy; - u8 shutdown; u8 use_dma; struct spi_master *master;