dma: mmp_pdma: add protect when alloc/free phy channels

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>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index ad4b0a7..b1a2600 100644 (file)
--- 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);
@@ -769,6 +777,8 @@ 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;