Re: [PATCH 1/4] soc: fsl: qbman: FSL_DPAA depends on COMPILE_TEST

[Vladimir Oltean <olteanv@gmail.com>]

On Wed, Jun 26, 2024 at 08:09:53PM +0800, kernel test robot wrote:
> Hi Breno,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on herbert-cryptodev-2.6/master]
> [also build test WARNING on soc/for-next linus/master v6.10-rc5 next-20240625]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Breno-Leitao/crypto-caam-Depend-on-COMPILE_TEST-also/20240625-223834
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master
> patch link:    https://lore.kernel.org/r/20240624162128.1665620-1-leitao%40debian.org
> patch subject: [PATCH 1/4] soc: fsl: qbman: FSL_DPAA depends on COMPILE_TEST
> config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20240626/202406261920.l5pzM1rj-lkp@intel.com/config)
> compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240626/202406261920.l5pzM1rj-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202406261920.l5pzM1rj-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> drivers/net/ethernet/freescale/dpaa/dpaa_eth.c:3280:12: warning: stack frame size (16664) exceeds limit (2048) in 'dpaa_eth_probe' [-Wframe-larger-than]
>     3280 | static int dpaa_eth_probe(struct platform_device *pdev)
>          |            ^
>    1 warning generated.
> --
> >> drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c:454:12: warning: stack frame size (8264) exceeds limit (2048) in 'dpaa_set_coalesce' [-Wframe-larger-than]
>      454 | static int dpaa_set_coalesce(struct net_device *dev,
>          |            ^
>    1 warning generated.

Arrays of NR_CPUS elements are what it probably doesn't like?
In the attached Kconfig, CONFIG_NR_CPUS is 8192, which is clearly
excessive compared to the SoCs that the driver is written for and
expects to run on (1-24 cores).

static int dpaa_set_coalesce(struct net_device *dev,
			     struct ethtool_coalesce *c,
			     struct kernel_ethtool_coalesce *kernel_coal,
			     struct netlink_ext_ack *extack)
{
	const cpumask_t *cpus = qman_affine_cpus();
	bool needs_revert[NR_CPUS] = {false};
	...
}

static void dpaa_fq_setup(struct dpaa_priv *priv,
			  const struct dpaa_fq_cbs *fq_cbs,
			  struct fman_port *tx_port)
{
	int egress_cnt = 0, conf_cnt = 0, num_portals = 0, portal_cnt = 0, cpu;
	const cpumask_t *affine_cpus = qman_affine_cpus();
	u16 channels[NR_CPUS];
	...
}

While 'needs_revert' can probably easily be converted to a bitmask which
consumes 8 times less space, I don't know what to say about the "channels"
array. It could probably be rewritten to use dynamic allocation for the
array. I don't have any better idea...