From 4415b03abb0aacd937010f13310b7fa437b9ad7d Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 31 Jul 2014 09:34:06 +0900 Subject: [PATCH] dmaengine: shdma: Allocate cyclic sg list dynamically MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Simon Horman Signed-off-by: Vinod Koul --- 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 94b6bde6c86a..e427a03a0e8b 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, -- 2.25.1