[PATCH] drm: a6xx: avoid excessive stack usage

[Dmitry Baryshkov]

On Sat, Oct 19, 2024 at 03:01:46PM +0530, Akhil P Oommen wrote:
> On Fri, Oct 18, 2024 at 03:11:38PM +0000, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd at arndb.de>
> > 
> > Clang-19 and above sometimes end up with multiple copies of the large
> > a6xx_hfi_msg_bw_table structure on the stack. The problem is that
> > a6xx_hfi_send_bw_table() calls a number of device specific functions to
> > fill the structure, but these create another copy of the structure on
> > the stack which gets copied to the first.
> > 
> > If the functions get inlined, that busts the warning limit:
> > 
> > drivers/gpu/drm/msm/adreno/a6xx_hfi.c:631:12: error: stack frame size (1032) exceeds limit (1024) in 'a6xx_hfi_send_bw_table' [-Werror,-Wframe-larger-than]
> 
> Why does this warning says that the limit is 1024? 1024 bytes is too small, isn't it?

Kernel stacks are expected to be space limited, so 1024 is a logical
limit for a single function.


-- 
With best wishes
Dmitry