Commit 52126d4c authored by Christophe JAILLET's avatar Christophe JAILLET Committed by Vinod Koul
Browse files

dmaengine: Remove a useless mutex 



According to lib/idr.c,
   The IDA handles its own locking.  It is safe to call any of the IDA
   functions without synchronisation in your code.

so the 'chan_mutex' mutex can just be removed.
It is here only to protect some ida_alloc()/ida_free() calls.

Signed-off-by: default avatarChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/7180452c1d77b039e27b6f9418e0e7d9dd33c431.1644140845.git.christophe.jaillet@wanadoo.fr


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 2d7991fe

drivers/dma/dmaengine.c

+0 −7
Original line number Diff line number Diff line
@@ -1053,9 +1053,7 @@ static int __dma_async_device_channel_register(struct dma_device *device, 
	 * When the chan_id is a negative value, we are dynamically adding

	 * the channel. Otherwise we are static enumerating.

	 */

	mutex_lock(&device->chan_mutex);

	chan->chan_id = ida_alloc(&device->chan_ida, GFP_KERNEL);

	mutex_unlock(&device->chan_mutex);

	if (chan->chan_id < 0) {

		pr_err("%s: unable to alloc ida for chan: %d\n",

		       __func__, chan->chan_id);
@@ -1078,9 +1076,7 @@ static int __dma_async_device_channel_register(struct dma_device *device, 
	return 0;



 err_out_ida:

	mutex_lock(&device->chan_mutex);

	ida_free(&device->chan_ida, chan->chan_id);

	mutex_unlock(&device->chan_mutex);

 err_free_dev:

	kfree(chan->dev);

 err_free_local:
@@ -1113,9 +1109,7 @@ static void __dma_async_device_channel_unregister(struct dma_device *device, 
	device->chancnt--;

	chan->dev->chan = NULL;

	mutex_unlock(&dma_list_mutex);

	mutex_lock(&device->chan_mutex);

	ida_free(&device->chan_ida, chan->chan_id);

	mutex_unlock(&device->chan_mutex);

	device_unregister(&chan->dev->device);

	free_percpu(chan->local);

}
@@ -1250,7 +1244,6 @@ int dma_async_device_register(struct dma_device *device) 
	if (rc != 0)

		return rc;



	mutex_init(&device->chan_mutex);

	ida_init(&device->chan_ida);



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

include/linux/dmaengine.h

+0 −1
Original line number Diff line number Diff line
@@ -870,7 +870,6 @@ struct dma_device { 
	struct device *dev;

	struct module *owner;

	struct ida chan_ida;

	struct mutex chan_mutex;	/* to protect chan_ida */



	u32 src_addr_widths;

	u32 dst_addr_widths;