dmaengine: bcm2835-dma: Convert to use DMA pool

f93178291712 dmaengine: bcm2835-dma: Fix memory leak when stopping a
	     running transfer

Fixed the memleak, but introduced another issue: the terminate_all callback
might be called with interrupts disabled and the dma_free_coherent() is
not allowed to be called when IRQs are disabled.
Convert the driver to use dma_pool_* for managing the list of control
blocks for the transfer.

Fixes: f93178291712 ("dmaengine: bcm2835-dma: Fix memory leak when stopping a running transfer")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Matthias Reichl <hias@horus.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 54 insertions, 24 deletions

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index c92d6a70ccf3..996c4b00d323 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -31,6 +31,7 @@
  */
 #include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -62,6 +63,11 @@ struct bcm2835_dma_cb {
         uint32_t pad[2];
 };
 
+struct bcm2835_cb_entry {
+        struct bcm2835_dma_cb *cb;
+        dma_addr_t paddr;
+};
+
 struct bcm2835_chan {
         struct virt_dma_chan vc;
         struct list_head node;
@@ -72,18 +78,18 @@ struct bcm2835_chan {
 
         int ch;
         struct bcm2835_desc *desc;
+        struct dma_pool *cb_pool;
 
         void __iomem *chan_base;
         int irq_number;
 };
 
 struct bcm2835_desc {
+        struct bcm2835_chan *c;
         struct virt_dma_desc vd;
         enum dma_transfer_direction dir;
 
-        unsigned int control_block_size;
-        struct bcm2835_dma_cb *control_block_base;
-        dma_addr_t control_block_base_phys;
+        struct bcm2835_cb_entry *cb_list;
 
         unsigned int frames;
         size_t size;
@@ -143,10 +149,13 @@ static inline struct bcm2835_desc *to_bcm2835_dma_desc(
 static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
 {
         struct bcm2835_desc *desc = container_of(vd, struct bcm2835_desc, vd);
-        dma_free_coherent(desc->vd.tx.chan->device->dev,
-                        desc->control_block_size,
-                        desc->control_block_base,
-                        desc->control_block_base_phys);
+        int i;
+
+        for (i = 0; i < desc->frames; i++)
+                dma_pool_free(desc->c->cb_pool, desc->cb_list[i].cb,
+                              desc->cb_list[i].paddr);
+
+        kfree(desc->cb_list);
         kfree(desc);
 }
 
@@ -199,7 +208,7 @@ static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
 
         c->desc = d = to_bcm2835_dma_desc(&vd->tx);
 
-        writel(d->control_block_base_phys, c->chan_base + BCM2835_DMA_ADDR);
+        writel(d->cb_list[0].paddr, c->chan_base + BCM2835_DMA_ADDR);
         writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
 }
 
@@ -232,9 +241,16 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
 static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
 {
         struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+        struct device *dev = c->vc.chan.device->dev;
+
+        dev_dbg(dev, "Allocating DMA channel %d\n", c->ch);
 
-        dev_dbg(c->vc.chan.device->dev,
-                        "Allocating DMA channel %d\n", c->ch);
+        c->cb_pool = dma_pool_create(dev_name(dev), dev,
+                                     sizeof(struct bcm2835_dma_cb), 0, 0);
+        if (!c->cb_pool) {
+                dev_err(dev, "unable to allocate descriptor pool\n");
+                return -ENOMEM;
+        }
 
         return request_irq(c->irq_number,
                         bcm2835_dma_callback, 0, "DMA IRQ", c);
@@ -246,6 +262,7 @@ static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
 
         vchan_free_chan_resources(&c->vc);
         free_irq(c->irq_number, c);
+        dma_pool_destroy(c->cb_pool);
 
         dev_dbg(c->vc.chan.device->dev, "Freeing DMA channel %u\n", c->ch);
 }
@@ -261,8 +278,7 @@ static size_t bcm2835_dma_desc_size_pos(struct bcm2835_desc *d, dma_addr_t addr)
         size_t size;
 
         for (size = i = 0; i < d->frames; i++) {
-                struct bcm2835_dma_cb *control_block =
-                        &d->control_block_base[i];
+                struct bcm2835_dma_cb *control_block = d->cb_list[i].cb;
                 size_t this_size = control_block->length;
                 dma_addr_t dma;
 
@@ -343,6 +359,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
         dma_addr_t dev_addr;
         unsigned int es, sync_type;
         unsigned int frame;
+        int i;
 
         /* Grab configuration */
         if (!is_slave_direction(direction)) {
@@ -374,27 +391,31 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
         if (!d)
                 return NULL;
 
+        d->c = c;
         d->dir = direction;
         d->frames = buf_len / period_len;
 
-        /* Allocate memory for control blocks */
-        d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb);
-        d->control_block_base = dma_zalloc_coherent(chan->device->dev,
-                        d->control_block_size, &d->control_block_base_phys,
-                        GFP_NOWAIT);
-
-        if (!d->control_block_base) {
+        d->cb_list = kcalloc(d->frames, sizeof(*d->cb_list), GFP_KERNEL);
+        if (!d->cb_list) {
                 kfree(d);
                 return NULL;
         }
+        /* Allocate memory for control blocks */
+        for (i = 0; i < d->frames; i++) {
+                struct bcm2835_cb_entry *cb_entry = &d->cb_list[i];
+
+                cb_entry->cb = dma_pool_zalloc(c->cb_pool, GFP_ATOMIC,
+                                               &cb_entry->paddr);
+                if (!cb_entry->cb)
+                        goto error_cb;
+        }
 
         /*
          * Iterate over all frames, create a control block
          * for each frame and link them together.
          */
         for (frame = 0; frame < d->frames; frame++) {
-                struct bcm2835_dma_cb *control_block =
-                        &d->control_block_base[frame];
+                struct bcm2835_dma_cb *control_block = d->cb_list[frame].cb;
 
                 /* Setup adresses */
                 if (d->dir == DMA_DEV_TO_MEM) {
@@ -428,12 +449,21 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
                  * This DMA engine driver currently only supports cyclic DMA.
                  * Therefore, wrap around at number of frames.
                  */
-                control_block->next = d->control_block_base_phys +
-                        sizeof(struct bcm2835_dma_cb)
-                        * ((frame + 1) % d->frames);
+                control_block->next = d->cb_list[((frame + 1) % d->frames)].paddr;
         }
 
         return vchan_tx_prep(&c->vc, &d->vd, flags);
+error_cb:
+        i--;
+        for (; i >= 0; i--) {
+                struct bcm2835_cb_entry *cb_entry = &d->cb_list[i];
+
+                dma_pool_free(c->cb_pool, cb_entry->cb, cb_entry->paddr);
+        }
+
+        kfree(d->cb_list);
+        kfree(d);
+        return NULL;
 }
 
 static int bcm2835_dma_slave_config(struct dma_chan *chan,