3.16.83-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- kernel/trace/ftrace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -595,8 +595,7 @@ static int function_stat_show(struct seq #ifdef CONFIG_FUNCTION_GRAPH_TRACER seq_printf(m, " "); - avg = rec->time; - do_div(avg, rec->counter); + avg = div64_ul(rec->time, rec->counter); /* Sample standard deviation (s^2) */ if (rec->counter <= 1) @@ -613,7 +612,8 @@ static int function_stat_show(struct seq * Divide only 1000 for ns^2 -> us^2 conversion. * trace_print_graph_duration will divide 1000 again. */ - do_div(stddev, rec->counter * (rec->counter - 1) * 1000); + stddev = div64_ul(stddev, + rec->counter * (rec->counter - 1) * 1000); } trace_seq_init(&s);
