[PATCH 1/2] dma: mmp_pdma: add protect when alloc/free phy channels

From: Xiang Wang
Date: Mon Jun 03 2013 - 04:09:45 EST


From: Xiang Wang <wangx@xxxxxxxxxxx>

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@xxxxxxxxxxx>
---
drivers/dma/mmp_pdma.c | 41 +++++++++++++++++++++++++----------------
1 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index c26699f..21820c9 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 +238,29 @@ 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 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 +296,7 @@ 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;
- }
+ free_phy(chan);
dev_dbg(chan->dev, "no pending list\n");
return;
}
@@ -377,10 +393,7 @@ 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;
- }
+ free_phy(chan);
chan->idle = true;
chan->dev_addr = 0;
return 1;
@@ -411,10 +424,7 @@ 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;
- }
+ free_phy(chan);
return;
}

@@ -581,10 +591,7 @@ 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;
- }
+ 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 +784,8 @@ 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;
--
1.7.5.4

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