| Message ID | 1405691010-24995-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 4415b03abb0a |
| Delegated to: | Vinod Koul |
| Headers | show |
Hi > 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> > --- Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> > drivers/dma/sh/shdma-base.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > Morimoto-san, would you be able to test this change with the audio driver ? I > believe it's our only user of cyclic transfers. > > 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, > -- > Regards, > > Laurent Pinchart > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sh" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Best regards --- Kuninori Morimoto -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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,
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> --- drivers/dma/sh/shdma-base.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) Morimoto-san, would you be able to test this change with the audio driver ? I believe it's our only user of cyclic transfers.