diff mbox

[01/12] dma: mmp_pdma: add protect when alloc/free phy channels

Message ID 1375870770-14263-2-git-send-email-zonque@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Daniel Mack Aug. 7, 2013, 10:19 a.m. UTC 
From: Xiang Wang <wangx@marvell.com>

In mmp pdma, phy channels are allocated/freed dynamically
and frequently. But no proper protection is added.
Conflict will happen when multi-users are requesting phy
channels at the same time. Use spinlock to protect.

Signed-off-by: Xiang Wang <wangx@marvell.com>
---
 drivers/dma/mmp_pdma.c | 42 ++++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 16 deletions(-)

Comments

Ezequiel Garcia Aug. 7, 2013, 12:40 p.m. UTC | #1 
Daniel,

It's good to see this effort is moving forward!

I just have a minor nitpick.

On Wed, Aug 07, 2013 at 12:19:19PM +0200, Daniel Mack wrote:
>  
>  #define tx_to_mmp_pdma_desc(tx) container_of(tx, struct mmp_pdma_desc_sw, async_tx)
> @@ -219,6 +220,7 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>  	int prio, i;
>  	struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
>  	struct mmp_pdma_phy *phy;
> +	unsigned long flags;
>  
>  	/*
>  	 * dma channel priorities
> @@ -227,6 +229,8 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>  	 * ch 8 - 11, 24 - 27  <--> (2)
>  	 * ch 12 - 15, 28 - 31  <--> (3)
>  	 */
> +
> +	spin_lock_irqsave(&pdev->phy_lock, flags);
>  	for (prio = 0; prio <= (((pdev->dma_channels - 1) & 0xf) >> 2); prio++) {
>  		for (i = 0; i < pdev->dma_channels; i++) {
>  			if (prio != ((i & 0xf) >> 2))
> @@ -234,14 +238,30 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>  			phy = &pdev->phy[i];
>  			if (!phy->vchan) {
>  				phy->vchan = pchan;
> +				spin_unlock_irqrestore(&pdev->phy_lock, flags);

Isn't it better to goto ...

>  				return phy;
>  			}
>  		}
>  	}
>  

... here?

I think it's generally cleaner and less error-prone.

> +	spin_unlock_irqrestore(&pdev->phy_lock, flags);
>  	return NULL;
>  }
>
Daniel Mack Aug. 7, 2013, 12:42 p.m. UTC | #2 
On 07.08.2013 14:40, Ezequiel Garcia wrote:
> On Wed, Aug 07, 2013 at 12:19:19PM +0200, Daniel Mack wrote:
>>  
>>  #define tx_to_mmp_pdma_desc(tx) container_of(tx, struct mmp_pdma_desc_sw, async_tx)
>> @@ -219,6 +220,7 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  	int prio, i;
>>  	struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
>>  	struct mmp_pdma_phy *phy;
>> +	unsigned long flags;
>>  
>>  	/*
>>  	 * dma channel priorities
>> @@ -227,6 +229,8 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  	 * ch 8 - 11, 24 - 27  <--> (2)
>>  	 * ch 12 - 15, 28 - 31  <--> (3)
>>  	 */
>> +
>> +	spin_lock_irqsave(&pdev->phy_lock, flags);
>>  	for (prio = 0; prio <= (((pdev->dma_channels - 1) & 0xf) >> 2); prio++) {
>>  		for (i = 0; i < pdev->dma_channels; i++) {
>>  			if (prio != ((i & 0xf) >> 2))
>> @@ -234,14 +238,30 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  			phy = &pdev->phy[i];
>>  			if (!phy->vchan) {
>>  				phy->vchan = pchan;
>> +				spin_unlock_irqrestore(&pdev->phy_lock, flags);
> 
> Isn't it better to goto ...
> 
>>  				return phy;
>>  			}
>>  		}
>>  	}
>>  
> 
> ... here?
> 
> I think it's generally cleaner and less error-prone.

It's not my patch, but I can do that, unless Xiang Wang has objections.


Thanks,
Daniel
Daniel Mack Aug. 8, 2013, 8:35 a.m. UTC | #3 
On 07.08.2013 14:40, Ezequiel Garcia wrote:
> Daniel,
> 
> It's good to see this effort is moving forward!
> 
> I just have a minor nitpick.

I just realized that Vinod already commited this patch to his tree, so I
won't be sending it again.


Daniel

> 
> On Wed, Aug 07, 2013 at 12:19:19PM +0200, Daniel Mack wrote:
>>  
>>  #define tx_to_mmp_pdma_desc(tx) container_of(tx, struct mmp_pdma_desc_sw, async_tx)
>> @@ -219,6 +220,7 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  	int prio, i;
>>  	struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
>>  	struct mmp_pdma_phy *phy;
>> +	unsigned long flags;
>>  
>>  	/*
>>  	 * dma channel priorities
>> @@ -227,6 +229,8 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  	 * ch 8 - 11, 24 - 27  <--> (2)
>>  	 * ch 12 - 15, 28 - 31  <--> (3)
>>  	 */
>> +
>> +	spin_lock_irqsave(&pdev->phy_lock, flags);
>>  	for (prio = 0; prio <= (((pdev->dma_channels - 1) & 0xf) >> 2); prio++) {
>>  		for (i = 0; i < pdev->dma_channels; i++) {
>>  			if (prio != ((i & 0xf) >> 2))
>> @@ -234,14 +238,30 @@ static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
>>  			phy = &pdev->phy[i];
>>  			if (!phy->vchan) {
>>  				phy->vchan = pchan;
>> +				spin_unlock_irqrestore(&pdev->phy_lock, flags);
> 
> Isn't it better to goto ...
> 
>>  				return phy;
>>  			}
>>  		}
>>  	}
>>  
> 
> ... here?
> 
> I think it's generally cleaner and less error-prone.
> 
>> +	spin_unlock_irqrestore(&pdev->phy_lock, flags);
>>  	return NULL;
>>  }
>>  
>
diff mbox

Patch

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index c26699f..226158d 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -121,6 +121,7 @@  struct mmp_pdma_device {
 	struct device			*dev;
 	struct dma_device		device;
 	struct mmp_pdma_phy		*phy;
+	spinlock_t phy_lock; /* protect alloc/free phy channels */
 };
 
 #define tx_to_mmp_pdma_desc(tx) container_of(tx, struct mmp_pdma_desc_sw, async_tx)
@@ -219,6 +220,7 @@  static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
 	int prio, i;
 	struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
 	struct mmp_pdma_phy *phy;
+	unsigned long flags;
 
 	/*
 	 * dma channel priorities
@@ -227,6 +229,8 @@  static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
 	 * ch 8 - 11, 24 - 27  <--> (2)
 	 * ch 12 - 15, 28 - 31  <--> (3)
 	 */
+
+	spin_lock_irqsave(&pdev->phy_lock, flags);
 	for (prio = 0; prio <= (((pdev->dma_channels - 1) & 0xf) >> 2); prio++) {
 		for (i = 0; i < pdev->dma_channels; i++) {
 			if (prio != ((i & 0xf) >> 2))
@@ -234,14 +238,30 @@  static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
 			phy = &pdev->phy[i];
 			if (!phy->vchan) {
 				phy->vchan = pchan;
+				spin_unlock_irqrestore(&pdev->phy_lock, flags);
 				return phy;
 			}
 		}
 	}
 
+	spin_unlock_irqrestore(&pdev->phy_lock, flags);
 	return NULL;
 }
 
+static void mmp_pdma_free_phy(struct mmp_pdma_chan *pchan)
+{
+	struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
+	unsigned long flags;
+
+	if (!pchan->phy)
+		return;
+
+	spin_lock_irqsave(&pdev->phy_lock, flags);
+	pchan->phy->vchan = NULL;
+	pchan->phy = NULL;
+	spin_unlock_irqrestore(&pdev->phy_lock, flags);
+}
+
 /* desc->tx_list ==> pending list */
 static void append_pending_queue(struct mmp_pdma_chan *chan,
 					struct mmp_pdma_desc_sw *desc)
@@ -277,10 +297,7 @@  static void start_pending_queue(struct mmp_pdma_chan *chan)
 
 	if (list_empty(&chan->chain_pending)) {
 		/* chance to re-fetch phy channel with higher prio */
-		if (chan->phy) {
-			chan->phy->vchan = NULL;
-			chan->phy = NULL;
-		}
+		mmp_pdma_free_phy(chan);
 		dev_dbg(chan->dev, "no pending list\n");
 		return;
 	}
@@ -377,10 +394,7 @@  static int mmp_pdma_alloc_chan_resources(struct dma_chan *dchan)
 		dev_err(chan->dev, "unable to allocate descriptor pool\n");
 		return -ENOMEM;
 	}
-	if (chan->phy) {
-		chan->phy->vchan = NULL;
-		chan->phy = NULL;
-	}
+	mmp_pdma_free_phy(chan);
 	chan->idle = true;
 	chan->dev_addr = 0;
 	return 1;
@@ -411,10 +425,7 @@  static void mmp_pdma_free_chan_resources(struct dma_chan *dchan)
 	chan->desc_pool = NULL;
 	chan->idle = true;
 	chan->dev_addr = 0;
-	if (chan->phy) {
-		chan->phy->vchan = NULL;
-		chan->phy = NULL;
-	}
+	mmp_pdma_free_phy(chan);
 	return;
 }
 
@@ -581,10 +592,7 @@  static int mmp_pdma_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,
 	switch (cmd) {
 	case DMA_TERMINATE_ALL:
 		disable_chan(chan->phy);
-		if (chan->phy) {
-			chan->phy->vchan = NULL;
-			chan->phy = NULL;
-		}
+		mmp_pdma_free_phy(chan);
 		spin_lock_irqsave(&chan->desc_lock, flags);
 		mmp_pdma_free_desc_list(chan, &chan->chain_pending);
 		mmp_pdma_free_desc_list(chan, &chan->chain_running);
@@ -777,6 +785,8 @@  static int mmp_pdma_probe(struct platform_device *op)
 		return -ENOMEM;
 	pdev->dev = &op->dev;
 
+	spin_lock_init(&pdev->phy_lock);
+
 	iores = platform_get_resource(op, IORESOURCE_MEM, 0);
 	if (!iores)
 		return -EINVAL;