Re: [PATCH] [net-next] cxgb4: reduce kernel stack usage in cudbg_collect_mem_region()

[David Miller]

From: Arnd Bergmann <arnd@xxxxxxxx>
Date: Fri, 12 Jul 2019 11:06:33 +0200

> The cudbg_collect_mem_region() and cudbg_read_fw_mem() both use several
> hundred kilobytes of kernel stack space. One gets inlined into the other,
> which causes the stack usage to be combined beyond the warning limit
> when building with clang:
> 
> drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c:1057:12: error: stack frame size of 1244 bytes in function 'cudbg_collect_mem_region' [-Werror,-Wframe-larger-than=]
> 
> Restructuring cudbg_collect_mem_region() lets clang do the same
> optimization that gcc does and reuse the stack slots as it can
> see that the large variables are never used together.
> 
> A better fix might be to avoid using cudbg_meminfo on the stack
> altogether, but that requires a larger rewrite.
> 
> Fixes: a1c69520f785 ("cxgb4: collect MC memory dump")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Applied.