From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992760AbXCHADK (ORCPT ); Wed, 7 Mar 2007 19:03:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992784AbXCHADK (ORCPT ); Wed, 7 Mar 2007 19:03:10 -0500 Received: from out-smtp.licor.com ([63.151.144.205]:3044 "HELO out-smtp.licor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S2992760AbXCHADJ (ORCPT ); Wed, 7 Mar 2007 19:03:09 -0500 X-Greylist: delayed 903 seconds by postgrey-1.27 at vger.kernel.org; Wed, 07 Mar 2007 19:03:08 EST Message-ID: <45EF4F32.2050601@licor.com> Date: Wed, 07 Mar 2007 17:48:02 -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: [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> In-Reply-To: <200703071031.39997.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 --- This patch is against 2.6.19.2, but should apply cleanly to 2.6.20 --- linux-2.6.19.2/include/linux/spi/spi_bitbang.h.orig 2007-03-07 15:08:13.000000000 -0600 +++ linux-2.6.19.2/include/linux/spi/spi_bitbang.h 2007-03-07 15:08:27.000000000 -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; --- linux-2.6.19.2/drivers/spi/spi_bitbang.c.orig 2007-03-07 15:03:42.000000000 -0600 +++ linux-2.6.19.2/drivers/spi/spi_bitbang.c 2007-03-07 15:14:10.000000000 -0600 @@ -301,10 +301,6 @@ static void bitbang_work(void *_bitbang) 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) { @@ -409,8 +405,6 @@ 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) @@ -505,28 +499,10 @@ 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); - - 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; - } + spi_unregister_master(bitbang->master); destroy_workqueue(bitbang->workqueue); - spi_unregister_master(bitbang->master); - return 0; } EXPORT_SYMBOL_GPL(spi_bitbang_stop);