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Commit 07f2211e authored by Dan Williams's avatar Dan Williams
Browse files

dmaengine: remove dependency on async_tx 



async_tx.ko is a consumer of dma channels.  A circular dependency arises
if modules in drivers/dma rely on common code in async_tx.ko.  It
prevents either module from being unloaded.

Move dma_wait_for_async_tx and async_tx_run_dependencies to dmaeninge.o
where they should have been from the beginning.

Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 28405d8d

crypto/async_tx/async_tx.c

+0 −75
Original line number Diff line number Diff line
@@ -72,81 +72,6 @@ void async_tx_issue_pending_all(void) 
}

EXPORT_SYMBOL_GPL(async_tx_issue_pending_all);



/* dma_wait_for_async_tx - spin wait for a transcation to complete

 * @tx: transaction to wait on

 */

enum dma_status

dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)

{

	enum dma_status status;

	struct dma_async_tx_descriptor *iter;

	struct dma_async_tx_descriptor *parent;



	if (!tx)

		return DMA_SUCCESS;



	/* poll through the dependency chain, return when tx is complete */

	do {

		iter = tx;



		/* find the root of the unsubmitted dependency chain */

		do {

			parent = iter->parent;

			if (!parent)

				break;

			else

				iter = parent;

		} while (parent);



		/* there is a small window for ->parent == NULL and

		 * ->cookie == -EBUSY

		 */

		while (iter->cookie == -EBUSY)

			cpu_relax();



		status = dma_sync_wait(iter->chan, iter->cookie);

	} while (status == DMA_IN_PROGRESS || (iter != tx));



	return status;

}

EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);



/* async_tx_run_dependencies - helper routine for dma drivers to process

 *	(start) dependent operations on their target channel

 * @tx: transaction with dependencies

 */

void async_tx_run_dependencies(struct dma_async_tx_descriptor *tx)

{

	struct dma_async_tx_descriptor *dep = tx->next;

	struct dma_async_tx_descriptor *dep_next;

	struct dma_chan *chan;



	if (!dep)

		return;



	chan = dep->chan;



	/* keep submitting up until a channel switch is detected

	 * in that case we will be called again as a result of

	 * processing the interrupt from async_tx_channel_switch

	 */

	for (; dep; dep = dep_next) {

		spin_lock_bh(&dep->lock);

		dep->parent = NULL;

		dep_next = dep->next;

		if (dep_next && dep_next->chan == chan)

			dep->next = NULL; /* ->next will be submitted */

		else

			dep_next = NULL; /* submit current dep and terminate */

		spin_unlock_bh(&dep->lock);



		dep->tx_submit(dep);

	}



	chan->device->device_issue_pending(chan);

}

EXPORT_SYMBOL_GPL(async_tx_run_dependencies);



static void

free_dma_chan_ref(struct rcu_head *rcu)

{

drivers/dma/Kconfig

+0 −2
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ config INTEL_IOATDMA 
config INTEL_IOP_ADMA

	tristate "Intel IOP ADMA support"

	depends on ARCH_IOP32X || ARCH_IOP33X || ARCH_IOP13XX

	select ASYNC_CORE

	select DMA_ENGINE

	help

	  Enable support for the Intel(R) IOP Series RAID engines.
@@ -59,7 +58,6 @@ config FSL_DMA 
config MV_XOR

	bool "Marvell XOR engine support"

	depends on PLAT_ORION

	select ASYNC_CORE

	select DMA_ENGINE

	---help---

	  Enable support for the Marvell XOR engine.

drivers/dma/dmaengine.c

+84 −0
Original line number Diff line number Diff line
@@ -626,6 +626,90 @@ void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx, 
}

EXPORT_SYMBOL(dma_async_tx_descriptor_init);



/* dma_wait_for_async_tx - spin wait for a transaction to complete

 * @tx: in-flight transaction to wait on

 *

 * This routine assumes that tx was obtained from a call to async_memcpy,

 * async_xor, async_memset, etc which ensures that tx is "in-flight" (prepped

 * and submitted).  Walking the parent chain is only meant to cover for DMA

 * drivers that do not implement the DMA_INTERRUPT capability and may race with

 * the driver's descriptor cleanup routine.

 */

enum dma_status

dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)

{

	enum dma_status status;

	struct dma_async_tx_descriptor *iter;

	struct dma_async_tx_descriptor *parent;



	if (!tx)

		return DMA_SUCCESS;



	WARN_ONCE(tx->parent, "%s: speculatively walking dependency chain for"

		  " %s\n", __func__, dev_name(&tx->chan->dev));



	/* poll through the dependency chain, return when tx is complete */

	do {

		iter = tx;



		/* find the root of the unsubmitted dependency chain */

		do {

			parent = iter->parent;

			if (!parent)

				break;

			else

				iter = parent;

		} while (parent);



		/* there is a small window for ->parent == NULL and

		 * ->cookie == -EBUSY

		 */

		while (iter->cookie == -EBUSY)

			cpu_relax();



		status = dma_sync_wait(iter->chan, iter->cookie);

	} while (status == DMA_IN_PROGRESS || (iter != tx));



	return status;

}

EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);



/* dma_run_dependencies - helper routine for dma drivers to process

 *	(start) dependent operations on their target channel

 * @tx: transaction with dependencies

 */

void dma_run_dependencies(struct dma_async_tx_descriptor *tx)

{

	struct dma_async_tx_descriptor *dep = tx->next;

	struct dma_async_tx_descriptor *dep_next;

	struct dma_chan *chan;



	if (!dep)

		return;



	chan = dep->chan;



	/* keep submitting up until a channel switch is detected

	 * in that case we will be called again as a result of

	 * processing the interrupt from async_tx_channel_switch

	 */

	for (; dep; dep = dep_next) {

		spin_lock_bh(&dep->lock);

		dep->parent = NULL;

		dep_next = dep->next;

		if (dep_next && dep_next->chan == chan)

			dep->next = NULL; /* ->next will be submitted */

		else

			dep_next = NULL; /* submit current dep and terminate */

		spin_unlock_bh(&dep->lock);



		dep->tx_submit(dep);

	}



	chan->device->device_issue_pending(chan);

}

EXPORT_SYMBOL_GPL(dma_run_dependencies);



static int __init dma_bus_init(void)

{

	mutex_init(&dma_list_mutex);

drivers/dma/iop-adma.c

+1 −2
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ 


#include <linux/init.h>

#include <linux/module.h>

#include <linux/async_tx.h>

#include <linux/delay.h>

#include <linux/dma-mapping.h>

#include <linux/spinlock.h>
@@ -116,7 +115,7 @@ iop_adma_run_tx_complete_actions(struct iop_adma_desc_slot *desc, 
	}



	/* run dependent operations */

	async_tx_run_dependencies(&desc->async_tx);

	dma_run_dependencies(&desc->async_tx);



	return cookie;

}

drivers/dma/mv_xor.c

+1 −2
Original line number Diff line number Diff line
@@ -18,7 +18,6 @@ 


#include <linux/init.h>

#include <linux/module.h>

#include <linux/async_tx.h>

#include <linux/delay.h>

#include <linux/dma-mapping.h>

#include <linux/spinlock.h>
@@ -340,7 +339,7 @@ mv_xor_run_tx_complete_actions(struct mv_xor_desc_slot *desc, 
	}



	/* run dependent operations */

	async_tx_run_dependencies(&desc->async_tx);

	dma_run_dependencies(&desc->async_tx);



	return cookie;

}