Hi John, Sorry I didn't reply to this sooner, too many patches :/
John Hubbard <jhubb...@nvidia.com> writes: > 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=] Oddly I don't see that warning in my builds, eg with GCC9: https://travis-ci.org/linuxppc/linux/jobs/604870722 > 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. It _probably_ doesn't, because it only increments the index when the chip_id of the CPU changes, ie. it doesn't create a chip for every CPU. But I agree it's flaky the way it's written. > Fix both problems by dynamically allocating based on CONFIG_NR_CPUS. Shouldn't it use num_possible_cpus() ? Given the for loop is over possible CPUs that seems like the upper bound. In practice it should be lower because some CPUs will share a chip. cheers > 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> > --- > > Changes since v1: includes Viresh's review commit fixes. > > 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..5b2e968cb5ea 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(*chip), GFP_KERNEL); > + if (!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
