Re: [PATCH] [v2] dmaengine: dw-edma: reduce stack usage after debugfs rework

From: Vinod Koul
Date: Fri Feb 10 2023 - 03:52:41 EST


On 30-01-23, 19:50, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> After the dw_edma_debugfs_entry arrays are no longer compile-time
> constant, they take up space on the stack, which exceeds the warning
> limit after inlining:
>
> drivers/dma/dw-edma/dw-edma-v0-debugfs.c:280:6: error: stack frame size (1784) exceeds limit (1400) in 'dw_edma_v0_debugfs_on' [-Werror,-Wframe-larger-than]
> void dw_edma_v0_debugfs_on(struct dw_edma *dw)
>
> Work around this by preventing dw_edma_debugfs_regs_{wr,rd} from both
> being inlined together, which cuts the stack frame size in half and
> makes it fit below the warning limit.
>
> Fixes: 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> v2: rebase on top of dmaengine tree

I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so
I am going to defer this after merge window

> ---
> drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> index 42380bf64a70..6542060bd01a 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> @@ -136,7 +136,8 @@ static void dw_edma_debugfs_regs_ch(struct dw_edma *dw, enum dw_edma_dir dir,
> dw_edma_debugfs_create_x32(dw, debugfs_regs, nr_entries, dent);
> }
>
> -static void dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
> +static noinline_for_stack void
> +dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
> {
> const struct dw_edma_debugfs_entry debugfs_regs[] = {
> /* eDMA global registers */
> @@ -197,7 +198,8 @@ static void dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
> }
> }
>
> -static void dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
> +static noinline_for_stack void
> +dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
> {
> const struct dw_edma_debugfs_entry debugfs_regs[] = {
> /* eDMA global registers */
> --
> 2.39.0

--
~Vinod