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dmaengine: shdma: Allocate cyclic sg list dynamically

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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@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Laurent Pinchart 2014-07-31 09:34:06 +09:00 committed by Vinod Koul
parent c091ff51b4
commit 4415b03abb
1 changed files with 15 additions and 2 deletions
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17
drivers/dma/sh/shdma-base.c
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@ -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,