Commit fb37f137 authored Feb 25, 2016 by Alexandre Bailon Committed by Greg Kroah-Hartman Feb 25, 2016

greybus: loopback: Fix averaging



Currently, we are adding 0.5 to the average to round the average.
But we are using the remainder to calculate the decimal, so we do not
need to round the average.
In addition, use a u64 type for the remainder to avoid overflow
that might happen when stats->sum value is too big,
usually for requests per seconds and the throughput.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

parent ab81bb9c

drivers/staging/greybus/loopback.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -157,14 +157,15 @@ static ssize_t name##_avg_show(struct device *dev, \
		{ \
		struct gb_loopback_stats *stats; \
		struct gb_loopback *gb; \
		u64 avg; \
		u32 count, rem; \
		u64 avg, rem; \
		u32 count; \
		gb = dev_get_drvdata(dev); \
		stats = &gb->name; \
		count = stats->count ? stats->count : 1; \
		avg = stats->sum + count / 2; /* round closest */ \
		avg = stats->sum; \
		rem = do_div(avg, count); \
		return sprintf(buf, "%llu.%06u\n", avg, 1000000 * rem / count); \
		rem = 1000000 * rem / count; \
		return sprintf(buf, "%llu.%06u\n", avg, (u32)rem); \
		} \
		static DEVICE_ATTR_RO(name##_avg)