Putting large constant data on the stack causes unnecessary overhead
and stack usage:
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:285:6: error: stack frame size of 1376 bytes in function 'dw_edma_v0_debugfs_on' [-Werror,-Wframe-larger-than=]
Mark the variable 'static const' in order for the compiler to move it
into the .rodata section where it does no such harm.
Fixes: 305aebeff879 ("dmaengine: Add Synopsys eDMA IP version 0 debugfs support")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
index affa1ccaf7a0..42739508c0d8 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
@@ -48,7 +48,7 @@ static struct {
} lim[2][EDMA_V0_MAX_NR_CH];
struct debugfs_entries {
- char name[24];
+ const char *name;
dma_addr_t *reg;
};
--
2.20.0
Hi,
On Mon, Jun 17, 2019 at 14:16:45, Arnd Bergmann <[email protected]> wrote:
> Putting large constant data on the stack causes unnecessary overhead
> and stack usage:
>
> drivers/dma/dw-edma/dw-edma-v0-debugfs.c:285:6: error: stack frame size of 1376 bytes in function 'dw_edma_v0_debugfs_on' [-Werror,-Wframe-larger-than=]
I had that warning at the beginning of the development, that's why I
divided the debugfs entries into several subfunctions. Perhaps my
configuration has configured a bigger stack frame size than your
configuration.
>
> Mark the variable 'static const' in order for the compiler to move it
> into the .rodata section where it does no such harm.
Ok, sounds good.
Thanks.
>
> Fixes: 305aebeff879 ("dmaengine: Add Synopsys eDMA IP version 0 debugfs support")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> index affa1ccaf7a0..42739508c0d8 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
> @@ -48,7 +48,7 @@ static struct {
> } lim[2][EDMA_V0_MAX_NR_CH];
>
> struct debugfs_entries {
> - char name[24];
> + const char *name;
> dma_addr_t *reg;
> };
>
> --
> 2.20.0
On Fri, Jun 21, 2019 at 10:21 AM Gustavo Pimentel
<[email protected]> wrote:
> On Mon, Jun 17, 2019 at 14:16:45, Arnd Bergmann <[email protected]> wrote:
>
> > Putting large constant data on the stack causes unnecessary overhead
> > and stack usage:
> >
> > drivers/dma/dw-edma/dw-edma-v0-debugfs.c:285:6: error: stack frame size of 1376 bytes in function 'dw_edma_v0_debugfs_on' [-Werror,-Wframe-larger-than=]
>
> I had that warning at the beginning of the development, that's why I
> divided the debugfs entries into several subfunctions. Perhaps my
> configuration has configured a bigger stack frame size than your
> configuration.
I suspect the problem is CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE,
which is a farily new configuration option that has the unintended side-effect
of sometimes preventing the compiler combining local variables from functions
inlined into the caller. Adding 'noinline_for_stack' to the sub-functions would
have also prevented this, but I think just not having the strings on the
stack is better anyway.
Arnd