Re: [PATCH] cpufreq:powernv: Fix init_chip_info initialization in numa=off

On 27/07/21 11:46 am, Gautham R Shenoy wrote:

On Mon, Jul 26, 2021 at 10:37:57PM +0530, Pratik R. Sampat wrote:

quoted

In the numa=off kernel command-line configuration init_chip_info() loops
around the number of chips and attempts to copy the cpumask of that node
which is NULL for all iterations after the first chip.

Hence, store the cpu mask for each chip instead of derving cpumask from
node while populating the "chips" struct array and copy that to the
chips[i].mask

Cc: stable@vger.kernel.org
Fixes: 053819e0bf84 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
Signed-off-by: Pratik R. Sampat <redacted>
Reported-by: Shirisha Ganta <redacted>
---
  drivers/cpufreq/powernv-cpufreq.c | 15 +++++++++++++--
  1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 005600cef273..8ec10d9aed8f 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -1046,12 +1046,20 @@ static int init_chip_info(void)
  	unsigned int *chip;
  	unsigned int cpu, i;
  	unsigned int prev_chip_id = UINT_MAX;
+	cpumask_t *chip_cpu_mask;
  	int ret = 0;

  	chip = kcalloc(num_possible_cpus(), sizeof(*chip), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;

+	/* Allocate a chip cpu mask large enough to fit mask for all chips */
+	chip_cpu_mask = kcalloc(32, sizeof(cpumask_t), GFP_KERNEL);

I suppose by 32 you mean the maximum number of chips possible. You
could use a #define for that.

ack, I could #define the constant.

Otherwise, the patch looks good to me.

Reviewed-by: Gautham R. Shenoy <redacted>

Thanks
Pratik

quoted

+	if (!chip_cpu_mask) {
+		ret = -ENOMEM;
+		goto free_and_return;
+	}
+
  	for_each_possible_cpu(cpu) {
  		unsigned int id = cpu_to_chip_id(cpu);

@@ -1059,22 +1067,25 @@ static int init_chip_info(void)
  			prev_chip_id = id;
  			chip[nr_chips++] = id;
  		}
+		cpumask_set_cpu(cpu, &chip_cpu_mask[nr_chips-1]);
  	}

  	chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
  	if (!chips) {
  		ret = -ENOMEM;
-		goto free_and_return;
+		goto out_chip_cpu_mask;
  	}

  	for (i = 0; i < nr_chips; i++) {
  		chips[i].id = chip[i];
-		cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
+		cpumask_copy(&chips[i].mask, &chip_cpu_mask[i]);
  		INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
  		for_each_cpu(cpu, &chips[i].mask)
  			per_cpu(chip_info, cpu) =  &chips[i];
  	}

+out_chip_cpu_mask:
+	kfree(chip_cpu_mask);
  free_and_return:
  	kfree(chip);
  	return ret;

-- 
2.31.1