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authorDan Williams <dan.j.williams@intel.com>2009-01-06 13:38:14 -0500
committerDan Williams <dan.j.williams@intel.com>2009-01-06 13:38:14 -0500
commit2ba05622b8b143b0c95968ba59bddfbd6d2f2559 (patch)
treeb7b72d02a993ff2ba731d6608f4ab8ce87482bcb /drivers
parentbec085134e446577a983f17f57d642a88d1af53b (diff)
dmaengine: provide a common 'issue_pending_all' implementation
async_tx and net_dma each have open-coded versions of issue_pending_all, so provide a common routine in dmaengine. The implementation needs to walk the global device list, so implement rcu to allow dma_issue_pending_all to run lockless. Clients protect themselves from channel removal events by holding a dmaengine reference. Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/dma/dmaengine.c27
1 files changed, 24 insertions, 3 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 87a8cd4791ed..418eca28d472 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -70,6 +70,7 @@
70#include <linux/rcupdate.h> 70#include <linux/rcupdate.h>
71#include <linux/mutex.h> 71#include <linux/mutex.h>
72#include <linux/jiffies.h> 72#include <linux/jiffies.h>
73#include <linux/rculist.h>
73 74
74static DEFINE_MUTEX(dma_list_mutex); 75static DEFINE_MUTEX(dma_list_mutex);
75static LIST_HEAD(dma_device_list); 76static LIST_HEAD(dma_device_list);
@@ -366,6 +367,26 @@ struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
366EXPORT_SYMBOL(dma_find_channel); 367EXPORT_SYMBOL(dma_find_channel);
367 368
368/** 369/**
370 * dma_issue_pending_all - flush all pending operations across all channels
371 */
372void dma_issue_pending_all(void)
373{
374 struct dma_device *device;
375 struct dma_chan *chan;
376
377 WARN_ONCE(dmaengine_ref_count == 0,
378 "client called %s without a reference", __func__);
379
380 rcu_read_lock();
381 list_for_each_entry_rcu(device, &dma_device_list, global_node)
382 list_for_each_entry(chan, &device->channels, device_node)
383 if (chan->client_count)
384 device->device_issue_pending(chan);
385 rcu_read_unlock();
386}
387EXPORT_SYMBOL(dma_issue_pending_all);
388
389/**
369 * nth_chan - returns the nth channel of the given capability 390 * nth_chan - returns the nth channel of the given capability
370 * @cap: capability to match 391 * @cap: capability to match
371 * @n: nth channel desired 392 * @n: nth channel desired
@@ -490,7 +511,7 @@ void dma_async_client_register(struct dma_client *client)
490 err = dma_chan_get(chan); 511 err = dma_chan_get(chan);
491 if (err == -ENODEV) { 512 if (err == -ENODEV) {
492 /* module removed before we could use it */ 513 /* module removed before we could use it */
493 list_del_init(&device->global_node); 514 list_del_rcu(&device->global_node);
494 break; 515 break;
495 } else if (err) 516 } else if (err)
496 pr_err("dmaengine: failed to get %s: (%d)\n", 517 pr_err("dmaengine: failed to get %s: (%d)\n",
@@ -635,7 +656,7 @@ int dma_async_device_register(struct dma_device *device)
635 goto err_out; 656 goto err_out;
636 } 657 }
637 } 658 }
638 list_add_tail(&device->global_node, &dma_device_list); 659 list_add_tail_rcu(&device->global_node, &dma_device_list);
639 dma_channel_rebalance(); 660 dma_channel_rebalance();
640 mutex_unlock(&dma_list_mutex); 661 mutex_unlock(&dma_list_mutex);
641 662
@@ -677,7 +698,7 @@ void dma_async_device_unregister(struct dma_device *device)
677 struct dma_chan *chan; 698 struct dma_chan *chan;
678 699
679 mutex_lock(&dma_list_mutex); 700 mutex_lock(&dma_list_mutex);
680 list_del(&device->global_node); 701 list_del_rcu(&device->global_node);
681 dma_channel_rebalance(); 702 dma_channel_rebalance();
682 mutex_unlock(&dma_list_mutex); 703 mutex_unlock(&dma_list_mutex);
683 704