On 17-10-19, 17:04, John Hubbard wrote:
> The following build warning occurred on powerpc 64-bit builds:
>
> drivers/cpufreq/powernv-cpufreq.c: In function 'init_chip_info':
> drivers/cpufreq/powernv-cpufreq.c:1070:1: warning: the frame size of 1040
> bytes is larger than 1024 bytes [-Wframe-larger-than=]
How come we are catching this warning after 4 years ?
>
> This is due to putting 1024 bytes on the stack:
>
> unsigned int chip[256];
>
> ...and while looking at this, it also has a bug: it fails with a stack
> overrun, if CONFIG_NR_CPUS > 256.
>
> Fix both problems by dynamically allocating based on CONFIG_NR_CPUS.
>
> Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax
> capping at chip level")
> Cc: Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com>
> Cc: Preeti U Murthy <pre...@linux.vnet.ibm.com>
> Cc: Viresh Kumar <viresh.ku...@linaro.org>
> Cc: Rafael J. Wysocki <r...@rjwysocki.net>
> Cc: linux...@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: John Hubbard <jhubb...@nvidia.com>
> ---
>
> Hi,
>
> I have only compile-tested this, so I would appreciate if anyone
> could do a basic runtime test on it. But (famous last words) it
> seems simple enough that I'm confident it's correct. oh boy. :)
>
> thanks,
> John Hubbard
> NVIDIA
>
> drivers/cpufreq/powernv-cpufreq.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/powernv-cpufreq.c
> b/drivers/cpufreq/powernv-cpufreq.c
> index 6061850e59c9..78e04402125f 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -1041,9 +1041,14 @@ static struct cpufreq_driver powernv_cpufreq_driver = {
>
> static int init_chip_info(void)
> {
> - unsigned int chip[256];
> + unsigned int *chip;
> unsigned int cpu, i;
> unsigned int prev_chip_id = UINT_MAX;
> + int ret = 0;
> +
> + chip = kcalloc(CONFIG_NR_CPUS, sizeof(int), GFP_KERNEL);
sizeof(*chip)
> + if (!chips)
(!chip)
> + return -ENOMEM;
>
> for_each_possible_cpu(cpu) {
> unsigned int id = cpu_to_chip_id(cpu);
> @@ -1055,8 +1060,10 @@ static int init_chip_info(void)
> }
>
> chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
> - if (!chips)
> - return -ENOMEM;
> + if (!chips) {
> + ret = -ENOMEM;
> + goto free_and_return;
> + }
>
> for (i = 0; i < nr_chips; i++) {
> chips[i].id = chip[i];
> @@ -1066,7 +1073,9 @@ static int init_chip_info(void)
> per_cpu(chip_info, cpu) = &chips[i];
> }
>
> - return 0;
> +free_and_return:
> + kfree(chip);
> + return ret;
> }
>
> static inline void clean_chip_info(void)
> --
> 2.23.0
--
viresh
