tree cbc4ec6170b4d35a7b0f0987cce47f35adc9eaf7
parent cf7c50509dd76fa4c25966a6839554812eb53fe4
author Wen Yang <wenyang@linux.alibaba.com> 1578020568 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1578824655 +0100

ftrace: Avoid potential division by zero in function profiler

commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream.

The ftrace_profile->counter is unsigned long and
do_div truncates it to 32 bits, which means it can test
non-zero and be truncated to zero for division.
Fix this issue by using div64_ul() instead.

Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com

Cc: stable@vger.kernel.org
Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling")
Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>