diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/dmaengine.c | 217 | ||||
| -rw-r--r-- | drivers/dma/ioatdma.c | 1 | ||||
| -rw-r--r-- | drivers/dma/ioatdma.h | 3 |
3 files changed, 111 insertions, 110 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 404cc7b6e70..82489923af0 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -37,11 +37,11 @@ * 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 client has a channels list, it's only modified under the client->lock - * and in an RCU callback, so it's safe to read under rcu_read_lock(). + * Each client is responsible for keeping track of the channels it uses. See + * the definition of dma_event_callback in dmaengine.h. * * Each device has a kref, which is initialized to 1 when the device is - * registered. A kref_put is done for each class_device registered. When the + * registered. A kref_get is done for each class_device registered. When the * class_device is released, the coresponding 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 coresponding kref_put @@ -51,10 +51,12 @@ * 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 single reference is set when on an - * ADDED event, and removed with a REMOVE event. Net DMA client takes an - * extra reference per outstanding transaction. The relase function does a - * kref_put on the device. -ChrisL + * 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 unregesitered. 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 */ #include <linux/init.h> @@ -102,8 +104,19 @@ static ssize_t show_bytes_transferred(struct class_device *cd, char *buf) static ssize_t show_in_use(struct class_device *cd, char *buf) { struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev); + int in_use = 0; + + if (unlikely(chan->slow_ref) && + atomic_read(&chan->refcount.refcount) > 1) + in_use = 1; + else { + if (local_read(&(per_cpu_ptr(chan->local, + get_cpu())->refcount)) > 0) + in_use = 1; + put_cpu(); + } - return sprintf(buf, "%d\n", (chan->client ? 1 : 0)); + return sprintf(buf, "%d\n", in_use); } static struct class_device_attribute dma_class_attrs[] = { @@ -129,42 +142,53 @@ static struct class dma_devclass = { /* --- client and device registration --- */ +#define dma_chan_satisfies_mask(chan, mask) \ + __dma_chan_satisfies_mask((chan), &(mask)) +static int +__dma_chan_satisfies_mask(struct dma_chan *chan, dma_cap_mask_t *want) +{ + dma_cap_mask_t has; + + bitmap_and(has.bits, want->bits, chan->device->cap_mask.bits, + DMA_TX_TYPE_END); + return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END); +} + /** - * dma_client_chan_alloc - try to allocate a channel to a client + * dma_client_chan_alloc - try to allocate channels to a client * @client: &dma_client * * Called with dma_list_mutex held. */ -static struct dma_chan *dma_client_chan_alloc(struct dma_client *client) +static void dma_client_chan_alloc(struct dma_client *client) { struct dma_device *device; struct dma_chan *chan; - unsigned long flags; int desc; /* allocated descriptor count */ + enum dma_state_client ack; - /* Find a channel, any DMA engine will do */ - list_for_each_entry(device, &dma_device_list, global_node) { + /* Find a channel */ + list_for_each_entry(device, &dma_device_list, global_node) list_for_each_entry(chan, &device->channels, device_node) { - if (chan->client) + if (!dma_chan_satisfies_mask(chan, client->cap_mask)) continue; desc = chan->device->device_alloc_chan_resources(chan); if (desc >= 0) { - kref_get(&device->refcount); - kref_init(&chan->refcount); - chan->slow_ref = 0; - INIT_RCU_HEAD(&chan->rcu); - chan->client = client; - spin_lock_irqsave(&client->lock, flags); - list_add_tail_rcu(&chan->client_node, - &client->channels); - spin_unlock_irqrestore(&client->lock, flags); - return chan; + ack = client->event_callback(client, + chan, + DMA_RESOURCE_AVAILABLE); + + /* we are done once this client rejects + * an available resource + */ + if (ack == DMA_ACK) { + dma_chan_get(chan); + kref_get(&device->refcount); + } else if (ack == DMA_NAK) + return; } } - } - - return NULL; } enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie) @@ -193,7 +217,6 @@ void dma_chan_cleanup(struct kref *kref) { struct dma_chan *chan = container_of(kref, struct dma_chan, refcount); chan->device->device_free_chan_resources(chan); - chan->client = NULL; kref_put(&chan->device->refcount, dma_async_device_cleanup); } EXPORT_SYMBOL(dma_chan_cleanup); @@ -209,7 +232,7 @@ static void dma_chan_free_rcu(struct rcu_head *rcu) kref_put(&chan->refcount, dma_chan_cleanup); } -static void dma_client_chan_free(struct dma_chan *chan) +static void dma_chan_release(struct dma_chan *chan) { atomic_add(0x7FFFFFFF, &chan->refcount.refcount); chan->slow_ref = 1; @@ -217,70 +240,57 @@ static void dma_client_chan_free(struct dma_chan *chan) } /** - * dma_chans_rebalance - reallocate channels to clients - * - * When the number of DMA channel in the system changes, - * channels need to be rebalanced among clients. + * dma_chans_notify_available - broadcast available channels to the clients */ -static void dma_chans_rebalance(void) +static void dma_clients_notify_available(void) { struct dma_client *client; - struct dma_chan *chan; - unsigned long flags; mutex_lock(&dma_list_mutex); - list_for_each_entry(client, &dma_client_list, global_node) { - while (client->chans_desired > client->chan_count) { - chan = dma_client_chan_alloc(client); - if (!chan) - break; - client->chan_count++; - client->event_callback(client, - chan, - DMA_RESOURCE_ADDED); - } - while (client->chans_desired < client->chan_count) { - spin_lock_irqsave(&client->lock, flags); - chan = list_entry(client->channels.next, - struct dma_chan, - client_node); - list_del_rcu(&chan->client_node); - spin_unlock_irqrestore(&client->lock, flags); - client->chan_count--; - client->event_callback(client, - chan, - DMA_RESOURCE_REMOVED); - dma_client_chan_free(chan); - } - } + list_for_each_entry(client, &dma_client_list, global_node) + dma_client_chan_alloc(client); mutex_unlock(&dma_list_mutex); } /** - * dma_async_client_register - allocate and register a &dma_client - * @event_callback: callback for notification of channel addition/removal + * dma_chans_notify_available - tell the clients that a channel is going away + * @chan: channel on its way out */ -struct dma_client *dma_async_client_register(dma_event_callback event_callback) +static void dma_clients_notify_removed(struct dma_chan *chan) { struct dma_client *client; + enum dma_state_client ack; - client = kzalloc(sizeof(*client), GFP_KERNEL); - if (!client) - return NULL; + mutex_lock(&dma_list_mutex); + + list_for_each_entry(client, &dma_client_list, global_node) { + ack = client->event_callback(client, chan, + DMA_RESOURCE_REMOVED); + + /* client was holding resources for this channel so + * free it + */ + if (ack == DMA_ACK) { + dma_chan_put(chan); + kref_put(&chan->device->refcount, + dma_async_device_cleanup); + } + } - INIT_LIST_HEAD(&client->channels); - spin_lock_init(&client->lock); - client->chans_desired = 0; - client->chan_count = 0; - client->event_callback = event_callback; + mutex_unlock(&dma_list_mutex); +} +/** + * dma_async_client_register - register a &dma_client + * @client: ptr to a client structure with valid 'event_callback' and 'cap_mask' + */ +void dma_async_client_register(struct dma_client *client) +{ mutex_lock(&dma_list_mutex); list_add_tail(&client->global_node, &dma_client_list); mutex_unlock(&dma_list_mutex); - - return client; } EXPORT_SYMBOL(dma_async_client_register); @@ -292,40 +302,42 @@ EXPORT_SYMBOL(dma_async_client_register); */ void dma_async_client_unregister(struct dma_client *client) { + struct dma_device *device; struct dma_chan *chan; + enum dma_state_client ack; if (!client) return; - rcu_read_lock(); - list_for_each_entry_rcu(chan, &client->channels, client_node) - dma_client_chan_free(chan); - rcu_read_unlock(); - mutex_lock(&dma_list_mutex); + /* free all channels the client is holding */ + list_for_each_entry(device, &dma_device_list, global_node) + list_for_each_entry(chan, &device->channels, device_node) { + ack = client->event_callback(client, chan, + DMA_RESOURCE_REMOVED); + + if (ack == DMA_ACK) { + dma_chan_put(chan); + kref_put(&chan->device->refcount, + dma_async_device_cleanup); + } + } + list_del(&client->global_node); mutex_unlock(&dma_list_mutex); - - kfree(client); - dma_chans_rebalance(); } EXPORT_SYMBOL(dma_async_client_unregister); /** - * dma_async_client_chan_request - request DMA channels - * @client: &dma_client - * @number: count of DMA channels requested - * - * Clients call dma_async_client_chan_request() to specify how many - * DMA channels they need, 0 to free all currently allocated. - * The resulting allocations/frees are indicated to the client via the - * event callback. + * dma_async_client_chan_request - send all available channels to the + * client that satisfy the capability mask + * @client - requester */ -void dma_async_client_chan_request(struct dma_client *client, - unsigned int number) +void dma_async_client_chan_request(struct dma_client *client) { - client->chans_desired = number; - dma_chans_rebalance(); + mutex_lock(&dma_list_mutex); + dma_client_chan_alloc(client); + mutex_unlock(&dma_list_mutex); } EXPORT_SYMBOL(dma_async_client_chan_request); @@ -386,13 +398,16 @@ int dma_async_device_register(struct dma_device *device) } kref_get(&device->refcount); + kref_init(&chan->refcount); + chan->slow_ref = 0; + INIT_RCU_HEAD(&chan->rcu); } mutex_lock(&dma_list_mutex); list_add_tail(&device->global_node, &dma_device_list); mutex_unlock(&dma_list_mutex); - dma_chans_rebalance(); + dma_clients_notify_available(); return 0; @@ -428,26 +443,16 @@ static void dma_async_device_cleanup(struct kref *kref) void dma_async_device_unregister(struct dma_device *device) { struct dma_chan *chan; - unsigned long flags; mutex_lock(&dma_list_mutex); list_del(&device->global_node); mutex_unlock(&dma_list_mutex); list_for_each_entry(chan, &device->channels, device_node) { - if (chan->client) { - spin_lock_irqsave(&chan->client->lock, flags); - list_del(&chan->client_node); - chan->client->chan_count--; - spin_unlock_irqrestore(&chan->client->lock, flags); - chan->client->event_callback(chan->client, - chan, - DMA_RESOURCE_REMOVED); - dma_client_chan_free(chan); - } + dma_clients_notify_removed(chan); class_device_unregister(&chan->class_dev); + dma_chan_release(chan); } - dma_chans_rebalance(); kref_put(&device->refcount, dma_async_device_cleanup); wait_for_completion(&device->done); diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c index 17104493028..81810b3042f 100644 --- a/drivers/dma/ioatdma.c +++ b/drivers/dma/ioatdma.c @@ -72,7 +72,6 @@ static int enumerate_dma_channels(struct ioat_device *device) INIT_LIST_HEAD(&ioat_chan->used_desc); /* This should be made common somewhere in dmaengine.c */ ioat_chan->common.device = &device->common; - ioat_chan->common.client = NULL; list_add_tail(&ioat_chan->common.device_node, &device->common.channels); } diff --git a/drivers/dma/ioatdma.h b/drivers/dma/ioatdma.h index d3f69bb15fa..d3726478031 100644 --- a/drivers/dma/ioatdma.h +++ b/drivers/dma/ioatdma.h @@ -30,9 +30,6 @@ #define IOAT_LOW_COMPLETION_MASK 0xffffffc0 -extern struct list_head dma_device_list; -extern struct list_head dma_client_list; - /** * struct ioat_device - internal representation of a IOAT device * @pdev: PCI-Express device |