Commit d988ff94 authored May 08, 2009 by Steven Rostedt Committed by Steven Rostedt May 11, 2009

ring-buffer: check for divide by zero in ring-buffer-benchmark



Although we check if "missed" is not zero, we divide by hit + missed,
and the addition can possible overflow and become a divide by zero.

This patch checks for this case, and will report it when it happens
then modify "hit" to make the calculation be non zero.

[ Impact: prevent possible divide by zero in ring-buffer-benchmark ]

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 5a772b2b

kernel/trace/ring_buffer_benchmark.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -294,6 +294,12 @@ static void ring_buffer_producer(void)

		pr_info("Total iterations per millisec: %ld\n", hit + missed);

		/* it is possible that hit + missed will overflow and be zero */
		if (!(hit + missed)) {
		pr_info("hit + missed overflowed and totalled zero!\n");
		hit--; /* make it non zero */
		}

		/* Caculate the average time in nanosecs */
		avg = NSEC_PER_MSEC / (hit + missed);
		pr_info("%ld ns per entry\n", avg);