Commit 2324a669 authored Oct 30, 2019 by John Hubbard Committed by Greg Kroah-Hartman Dec 17, 2019

cpufreq: powernv: fix stack bloat and hard limit on number of CPUs

commit db0d32d84031188443e25edbd50a71a6e7ac5d1d upstream.

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=]

This is with a cross-compiler based on gcc 8.1.0, which I got from:
  https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/



The warning is due to putting 1024 bytes on the stack:

    unsigned int chip[256];

...and it's also undesirable to have a hard limit on the number of
CPUs here.

Fix both problems by dynamically allocating based on num_possible_cpus,
as recommended by Michael Ellerman.

Fixes: 053819e0 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.10+ <stable@vger.kernel.org> # 4.10+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b1d06da3

drivers/cpufreq/powernv-cpufreq.c

+13 −4

Original line number	Diff line number	Diff line
		@@ -1042,9 +1042,14 @@ 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(num_possible_cpus(), sizeof(*chip), GFP_KERNEL);
		if (!chip)
		return -ENOMEM;

		for_each_possible_cpu(cpu) {
		unsigned int id = cpu_to_chip_id(cpu);
		@@ -1056,8 +1061,10 @@ 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];
		@@ -1067,7 +1074,9 @@ 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)