hwmon: ibmaem: Use ktime_get_ns() (d659f9b1) · Commits · 戴 / test

Using the wall clock time for delta time calculations is wrong to begin with because wall clock time can be set from userspace and NTP. Such data wants to be based on clock monotonic. The calculations also are done on a nanosecond basis. Use the nanoseconds based interface right away. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Cc: Jean Delvare <jdelvare@suse.de> Acked-by:

Jean Delvare <jdelvare@suse.de> Signed-off-by:

John Stultz <john.stultz@linaro.org>

drivers/hwmon/ibmaem.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -842,11 +842,10 @@ static ssize_t aem_show_power(struct device *dev,
		struct aem_data *data = dev_get_drvdata(dev);
		u64 before, after, delta, time;
		signed long leftover;
		struct timespec b, a;

		mutex_lock(&data->lock);
		update_aem_energy_one(data, attr->index);
		getnstimeofday(&b);
		time = ktime_get_ns();
		before = data->energy[attr->index];

		leftover = schedule_timeout_interruptible(
		@@ -858,11 +857,10 @@ static ssize_t aem_show_power(struct device *dev,
		}

		update_aem_energy_one(data, attr->index);
		getnstimeofday(&a);
		time = ktime_get_ns() - time;
		after = data->energy[attr->index];
		mutex_unlock(&data->lock);

		time = timespec_to_ns(&a) - timespec_to_ns(&b);
		delta = (after - before) * UJ_PER_MJ;

		return sprintf(buf, "%llu\n",

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