sched: Fix possible divide by zero in avg_atom() calculation
authorMateusz Guzik <mguzik@redhat.com>
Sat, 14 Jun 2014 13:00:09 +0000 (15:00 +0200)
committerIngo Molnar <mingo@kernel.org>
Wed, 16 Jul 2014 11:36:07 +0000 (13:36 +0200)
commitb0ab99e7736af88b8ac1b7ae50ea287fffa2badc
treeaee41b518d3cef411ebdf4bf385d28858a5fa759
parentb6220ad66bcd4a50737eb3c08e9466aa44f3bc98
sched: Fix possible divide by zero in avg_atom() calculation

proc_sched_show_task() does:

  if (nr_switches)
do_div(avg_atom, nr_switches);

nr_switches is unsigned long and do_div truncates it to 32 bits, which
means it can test non-zero on e.g. x86-64 and be truncated to zero for
division.

Fix the problem by using div64_ul() instead.

As a side effect calculations of avg_atom for big nr_switches are now correct.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/sched/debug.c