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authorDan Williams <dan.j.williams@intel.com>2009-01-06 11:38:14 -0700
committerDan Williams <dan.j.williams@intel.com>2009-01-06 11:38:14 -0700
commit2ba05622b8b143b0c95968ba59bddfbd6d2f2559 (patch)
treeb7b72d02a993ff2ba731d6608f4ab8ce87482bcb /drivers/dma
parentbec085134e446577a983f17f57d642a88d1af53b (diff)
downloadop-kernel-dev-2ba05622b8b143b0c95968ba59bddfbd6d2f2559.zip
op-kernel-dev-2ba05622b8b143b0c95968ba59bddfbd6d2f2559.tar.gz
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/dma')
-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 87a8cd4..418eca2 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -70,6 +70,7 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/jiffies.h>
+#include <linux/rculist.h>
static DEFINE_MUTEX(dma_list_mutex);
static LIST_HEAD(dma_device_list);
@@ -366,6 +367,26 @@ struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
EXPORT_SYMBOL(dma_find_channel);
/**
+ * dma_issue_pending_all - flush all pending operations across all channels
+ */
+void dma_issue_pending_all(void)
+{
+ struct dma_device *device;
+ struct dma_chan *chan;
+
+ WARN_ONCE(dmaengine_ref_count == 0,
+ "client called %s without a reference", __func__);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(device, &dma_device_list, global_node)
+ list_for_each_entry(chan, &device->channels, device_node)
+ if (chan->client_count)
+ device->device_issue_pending(chan);
+ rcu_read_unlock();
+}
+EXPORT_SYMBOL(dma_issue_pending_all);
+
+/**
* nth_chan - returns the nth channel of the given capability
* @cap: capability to match
* @n: nth channel desired
@@ -490,7 +511,7 @@ void dma_async_client_register(struct dma_client *client)
err = dma_chan_get(chan);
if (err == -ENODEV) {
/* module removed before we could use it */
- list_del_init(&device->global_node);
+ list_del_rcu(&device->global_node);
break;
} else if (err)
pr_err("dmaengine: failed to get %s: (%d)\n",
@@ -635,7 +656,7 @@ int dma_async_device_register(struct dma_device *device)
goto err_out;
}
}
- list_add_tail(&device->global_node, &dma_device_list);
+ list_add_tail_rcu(&device->global_node, &dma_device_list);
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
@@ -677,7 +698,7 @@ void dma_async_device_unregister(struct dma_device *device)
struct dma_chan *chan;
mutex_lock(&dma_list_mutex);
- list_del(&device->global_node);
+ list_del_rcu(&device->global_node);
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
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