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Commit 864498aa authored by Dan Williams's avatar Dan Williams
Browse files

dmaengine: use idr for registering dma device numbers 



This brings some predictability to dma device numbers, i.e. an rmmod/insmod
cycle may now result in /sys/class/dma/dma0chan0 being restored rather than
/sys/class/dma/dma1chan0 appearing.

Cc: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 41d5e59c

drivers/dma/dmaengine.c

+25 −2
Original line number Diff line number Diff line
@@ -57,10 +57,12 @@ 
#include <linux/mutex.h>

#include <linux/jiffies.h>

#include <linux/rculist.h>

#include <linux/idr.h>



static DEFINE_MUTEX(dma_list_mutex);

static LIST_HEAD(dma_device_list);

static long dmaengine_ref_count;

static struct idr dma_idr;



/* --- sysfs implementation --- */
@@ -147,6 +149,12 @@ static void chan_dev_release(struct device *dev) 
	struct dma_chan_dev *chan_dev;



	chan_dev = container_of(dev, typeof(*chan_dev), device);

	if (atomic_dec_and_test(chan_dev->idr_ref)) {

		mutex_lock(&dma_list_mutex);

		idr_remove(&dma_idr, chan_dev->dev_id);

		mutex_unlock(&dma_list_mutex);

		kfree(chan_dev->idr_ref);

	}

	kfree(chan_dev);

}
@@ -611,9 +619,9 @@ EXPORT_SYMBOL(dmaengine_put); 
 */

int dma_async_device_register(struct dma_device *device)

{

	static int id;

	int chancnt = 0, rc;

	struct dma_chan* chan;

	atomic_t *idr_ref;



	if (!device)

		return -ENODEV;
@@ -640,9 +648,20 @@ int dma_async_device_register(struct dma_device *device) 
	BUG_ON(!device->device_issue_pending);

	BUG_ON(!device->dev);



	idr_ref = kmalloc(sizeof(*idr_ref), GFP_KERNEL);

	if (!idr_ref)

		return -ENOMEM;

	atomic_set(idr_ref, 0);

 idr_retry:

	if (!idr_pre_get(&dma_idr, GFP_KERNEL))

		return -ENOMEM;

	mutex_lock(&dma_list_mutex);

	device->dev_id = id++;

	rc = idr_get_new(&dma_idr, NULL, &device->dev_id);

	mutex_unlock(&dma_list_mutex);

	if (rc == -EAGAIN)

		goto idr_retry;

	else if (rc != 0)

		return rc;



	/* represent channels in sysfs. Probably want devs too */

	list_for_each_entry(chan, &device->channels, device_node) {
@@ -659,6 +678,9 @@ int dma_async_device_register(struct dma_device *device) 
		chan->dev->device.class = &dma_devclass;

		chan->dev->device.parent = device->dev;

		chan->dev->chan = chan;

		chan->dev->idr_ref = idr_ref;

		chan->dev->dev_id = device->dev_id;

		atomic_inc(idr_ref);

		dev_set_name(&chan->dev->device, "dma%dchan%d",

			     device->dev_id, chan->chan_id);
@@ -971,6 +993,7 @@ EXPORT_SYMBOL_GPL(dma_run_dependencies); 


static int __init dma_bus_init(void)

{

	idr_init(&dma_idr);

	mutex_init(&dma_list_mutex);

	return class_register(&dma_devclass);

}

include/linux/dmaengine.h

+4 −0
Original line number Diff line number Diff line
@@ -140,10 +140,14 @@ struct dma_chan { 
 * struct dma_chan_dev - relate sysfs device node to backing channel device

 * @chan - driver channel device

 * @device - sysfs device

 * @dev_id - parent dma_device dev_id

 * @idr_ref - reference count to gate release of dma_device dev_id

 */

struct dma_chan_dev {

	struct dma_chan *chan;

	struct device device;

	int dev_id;

	atomic_t *idr_ref;

};



static inline const char *dma_chan_name(struct dma_chan *chan)