Messages in this thread Patch in this message | | | From | John Hubbard <> | Subject | [PATCH] cpufreq: powernv: fix stack bloat and NR_CPUS limitation | Date | Thu, 17 Oct 2019 17:04:31 -0700 |
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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 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.bhat@linux.vnet.ibm.com> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: linux-pm@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: John Hubbard <jhubbard@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); + if (!chips) + 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
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