From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756420AbYKNVj0 (ORCPT ); Fri, 14 Nov 2008 16:39:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756032AbYKNVfY (ORCPT ); Fri, 14 Nov 2008 16:35:24 -0500 Received: from mga11.intel.com ([192.55.52.93]:30395 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755895AbYKNVfU (ORCPT ); Fri, 14 Nov 2008 16:35:20 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.33,605,1220252400"; d="scan'208";a="639301358" From: Dan Williams Subject: [PATCH 12/13] dmaengine: remove 'bigref' infrastructure To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: maciej.sosnowski@intel.com, hskinnemoen@atmel.com, g.liakhovetski@gmx.de, nicolas.ferre@atmel.com Date: Fri, 14 Nov 2008 14:35:19 -0700 Message-ID: <20081114213518.32354.20458.stgit@dwillia2-linux.ch.intel.com> In-Reply-To: <20081114213300.32354.1154.stgit@dwillia2-linux.ch.intel.com> References: <20081114213300.32354.1154.stgit@dwillia2-linux.ch.intel.com> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reference counting is done at the module level so clients need not worry that a channel will leave while they are actively using dmaengine. Signed-off-by: Dan Williams --- drivers/dma/dmaengine.c | 86 +++++---------------------------------------- drivers/dma/iop-adma.c | 1 - drivers/dma/mv_xor.c | 1 - include/linux/dmaengine.h | 7 ---- 4 files changed, 9 insertions(+), 86 deletions(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 26f862c..a6c0d72 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -34,26 +34,15 @@ * The subsystem keeps a global list of dma_device structs it is protected by a * mutex, dma_list_mutex. * + * A subsystem can get access to a channel by calling dmaengine_get() followed + * by dma_find_channel(), or if it has need for an exclusive channel it can call + * dma_request_channel(). Once a channel is allocated a reference is taken + * against its corresponding driver to disable removal. + * * Each device has a channels list, which runs unlocked but is never modified * once the device is registered, it's just setup by the driver. * - * Each device has a kref, which is initialized to 1 when the device is - * registered. A kref_get is done for each device registered. When the - * device is released, the corresponding kref_put is done in the release - * method. Every time one of the device's channels is allocated to a client, - * a kref_get occurs. When the channel is freed, the corresponding kref_put - * happens. The device's release function does a completion, so - * unregister_device does a remove event, device_unregister, a kref_put - * for the first reference, then waits on the completion for all other - * references to finish. - * - * Each channel has an open-coded implementation of Rusty Russell's "bigref," - * with a kref and a per_cpu local_t. A dma_chan_get is called when a client - * signals that it wants to use a channel, and dma_chan_put is called when - * a channel is removed or a client using it is unregistered. A client can - * take extra references per outstanding transaction, as is the case with - * the NET DMA client. The release function does a kref_put on the device. - * -ChrisL, DanW + * See Documentation/dmaengine.txt for more details */ #include @@ -114,18 +103,9 @@ static struct device_attribute dma_attrs[] = { __ATTR_NULL }; -static void dma_async_device_cleanup(struct kref *kref); - -static void dma_dev_release(struct device *dev) -{ - struct dma_chan *chan = to_dma_chan(dev); - kref_put(&chan->device->refcount, dma_async_device_cleanup); -} - static struct class dma_devclass = { .name = "dma", .dev_attrs = dma_attrs, - .dev_release = dma_dev_release, }; /* --- client and device registration --- */ @@ -222,29 +202,6 @@ enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie) EXPORT_SYMBOL(dma_sync_wait); /** - * dma_chan_cleanup - release a DMA channel's resources - * @kref: kernel reference structure that contains the DMA channel device - */ -void dma_chan_cleanup(struct kref *kref) -{ - struct dma_chan *chan = container_of(kref, struct dma_chan, refcount); - kref_put(&chan->device->refcount, dma_async_device_cleanup); -} -EXPORT_SYMBOL(dma_chan_cleanup); - -static void dma_chan_free_rcu(struct rcu_head *rcu) -{ - struct dma_chan *chan = container_of(rcu, struct dma_chan, rcu); - - kref_put(&chan->refcount, dma_chan_cleanup); -} - -static void dma_chan_release(struct dma_chan *chan) -{ - call_rcu(&chan->rcu, dma_chan_free_rcu); -} - -/** * dma_cap_mask_all - enable iteration over all operation types */ static dma_cap_mask_t dma_cap_mask_all; @@ -622,8 +579,6 @@ int dma_async_device_register(struct dma_device *device) BUG_ON(!device->device_issue_pending); BUG_ON(!device->dev); - init_completion(&device->done); - kref_init(&device->refcount); device->dev_id = id++; /* represent channels in sysfs. Probably want devs too */ @@ -640,19 +595,11 @@ int dma_async_device_register(struct dma_device *device) rc = device_register(&chan->dev); if (rc) { - chancnt--; free_percpu(chan->local); chan->local = NULL; goto err_out; } - - /* One for the channel, one of the class device */ - kref_get(&device->refcount); - kref_get(&device->refcount); - kref_init(&chan->refcount); chan->client_count = 0; - chan->slow_ref = 0; - INIT_RCU_HEAD(&chan->rcu); } device->chancnt = chancnt; @@ -683,9 +630,7 @@ err_out: list_for_each_entry(chan, &device->channels, device_node) { if (chan->local == NULL) continue; - kref_put(&device->refcount, dma_async_device_cleanup); device_unregister(&chan->dev); - chancnt--; free_percpu(chan->local); } return rc; @@ -693,20 +638,11 @@ err_out: EXPORT_SYMBOL(dma_async_device_register); /** - * dma_async_device_cleanup - function called when all references are released - * @kref: kernel reference object - */ -static void dma_async_device_cleanup(struct kref *kref) -{ - struct dma_device *device; - - device = container_of(kref, struct dma_device, refcount); - complete(&device->done); -} - -/** * dma_async_device_unregister - unregisters DMA devices * @device: &dma_device + * + * This routine is called by dma driver exit routines, dmaengine holds module + * references to prevent it being called while channels are in use. */ void dma_async_device_unregister(struct dma_device *device) { @@ -722,11 +658,7 @@ void dma_async_device_unregister(struct dma_device *device) "%s called while %d clients hold a reference\n", __func__, chan->client_count); device_unregister(&chan->dev); - dma_chan_release(chan); } - - kref_put(&device->refcount, dma_async_device_cleanup); - wait_for_completion(&device->done); } EXPORT_SYMBOL(dma_async_device_unregister); diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c index 44c483e..6963400 100644 --- a/drivers/dma/iop-adma.c +++ b/drivers/dma/iop-adma.c @@ -1243,7 +1243,6 @@ static int __devinit iop_adma_probe(struct platform_device *pdev) spin_lock_init(&iop_chan->lock); INIT_LIST_HEAD(&iop_chan->chain); INIT_LIST_HEAD(&iop_chan->all_slots); - INIT_RCU_HEAD(&iop_chan->common.rcu); iop_chan->common.device = dma_dev; list_add_tail(&iop_chan->common.device_node, &dma_dev->channels); diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c index dabdc36..acb271d 100644 --- a/drivers/dma/mv_xor.c +++ b/drivers/dma/mv_xor.c @@ -1210,7 +1210,6 @@ static int __devinit mv_xor_probe(struct platform_device *pdev) INIT_LIST_HEAD(&mv_chan->chain); INIT_LIST_HEAD(&mv_chan->completed_slots); INIT_LIST_HEAD(&mv_chan->all_slots); - INIT_RCU_HEAD(&mv_chan->common.rcu); mv_chan->common.device = dma_dev; list_add_tail(&mv_chan->common.device_node, &dma_dev->channels); diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index ad9fd55..32edaf4 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -156,10 +156,6 @@ struct dma_chan { int chan_id; struct device dev; - struct kref refcount; - int slow_ref; - struct rcu_head rcu; - struct list_head device_node; struct dma_chan_percpu *local; int client_count; @@ -247,9 +243,6 @@ struct dma_device { dma_cap_mask_t cap_mask; int max_xor; - struct kref refcount; - struct completion done; - int dev_id; struct device *dev;