sched: Fix possible divide by zero in avg_atom() calculation
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 <971fb330b5cd41789124dc74f43ecb9c1cf6c0ff@redhat.com>
Signed-off-by: Peter Zijlstra <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Cc: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-971fb330b5cd41789124dc74f43ecb9c1cf6c0ff@redhat.com
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs