diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/dmaengine.c | 87 | ||||
| -rw-r--r-- | drivers/dma/iop-adma.c | 1 | ||||
| -rw-r--r-- | drivers/dma/mv_xor.c | 1 |
3 files changed, 9 insertions, 80 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 9fc91f973a9..b245c38dbec 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 <linux/init.h> @@ -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 --- */ @@ -233,29 +213,6 @@ 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; @@ -641,9 +598,6 @@ 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); - mutex_lock(&dma_list_mutex); device->dev_id = id++; mutex_unlock(&dma_list_mutex); @@ -662,19 +616,11 @@ 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; @@ -705,9 +651,7 @@ 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; @@ -715,20 +659,11 @@ 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 - unregister a DMA device * @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) { @@ -744,11 +679,7 @@ 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 c74ac9eb009..df0e37d70b3 100644 --- a/drivers/dma/iop-adma.c +++ b/drivers/dma/iop-adma.c @@ -1253,7 +1253,6 @@ 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 fbaa2f6225e..d35cbd1ff0b 100644 --- a/drivers/dma/mv_xor.c +++ b/drivers/dma/mv_xor.c @@ -1219,7 +1219,6 @@ 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); |