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authorThomas Gleixner <tglx@linutronix.de>2014-07-17 01:04:47 +0400
committerJohn Stultz <john.stultz@linaro.org>2014-07-24 02:01:44 +0400
commitd659f9b135fe26b966a6a4ad7281d35d7dbb1366 (patch)
tree3416ee5247b9dae698bedf918ecfa7e96c2d473b
parent5eaaed4fe23247f0784edc2973f04134f8180251 (diff)
downloadlinux-d659f9b135fe26b966a6a4ad7281d35d7dbb1366.tar.xz
hwmon: ibmaem: Use ktime_get_ns()
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>
-rw-r--r--drivers/hwmon/ibmaem.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c
index 632f1dc0fe1f..7a8a6fbf11ff 100644
--- a/drivers/hwmon/ibmaem.c
+++ b/drivers/hwmon/ibmaem.c
@@ -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",