From: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
The sg list used to prepare cyclic DMA descriptors is currently
allocated statically on the stack as an array of 32 elements. This makes
the shdma_prep_dma_cyclic() function consume a lot of stack space, as
reported by the compiler:
drivers/dma/sh/shdma-base.c: In function ‘shdma_prep_dma_cyclic’:
drivers/dma/sh/shdma-base.c:715:1: warning: the frame size of 1056 bytes
is larger than 1024 bytes [-Wframe-larger-than=]
Given the limited Linux kernel stack size, this could lead to stack
overflows. Fix the problem by allocating the sg list dynamically.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
---
drivers/dma/sh/shdma-base.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 94b6bde..e427a03 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -672,11 +672,12 @@ static struct dma_async_tx_descriptor *shdma_prep_dma_cyclic(
{
struct shdma_chan *schan = to_shdma_chan(chan);
struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
+ struct dma_async_tx_descriptor *desc;
const struct shdma_ops *ops = sdev->ops;
unsigned int sg_len = buf_len / period_len;
int slave_id = schan->slave_id;
dma_addr_t slave_addr;
- struct scatterlist sgl[SHDMA_MAX_SG_LEN];
+ struct scatterlist *sgl;
int i;
if (!chan)
@@ -700,7 +701,16 @@ static struct dma_async_tx_descriptor *shdma_prep_dma_cyclic(
slave_addr = ops->slave_addr(schan);
+ /*
+ * Allocate the sg list dynamically as it would consumer too much stack
+ * space.
+ */
+ sgl = kcalloc(sg_len, sizeof(*sgl), GFP_KERNEL);
+ if (!sgl)
+ return NULL;
+
sg_init_table(sgl, sg_len);
+
for (i = 0; i < sg_len; i++) {
dma_addr_t src = buf_addr + (period_len * i);
@@ -710,8 +720,11 @@ static struct dma_async_tx_descriptor *shdma_prep_dma_cyclic(
sg_dma_len(&sgl[i]) = period_len;
}
- return shdma_prep_sg(schan, sgl, sg_len, &slave_addr,
+ desc = shdma_prep_sg(schan, sgl, sg_len, &slave_addr,
direction, flags, true);
+
+ kfree(sgl);
+ return desc;
}
static int shdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
--
2.0.1
--
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