tree 783ff35f81d62549a685ab3715002c3def50c205
parent 34875887f360d7bd0b7f0a89f7c6d65eca616ee3
author Denys Vlasenko <dvlasenk@redhat.com> 1462563711 +0200
committer Jeff Kirsher <jeffrey.t.kirsher@intel.com> 1467219622 -0700

e1000e: prevent division by zero if TIMINCA is zero

Users report that under VMWare, er32(TIMINCA) returns zero.
This causes division by zero at init time as follows:

 ==>       incvalue = er32(TIMINCA) & E1000_TIMINCA_INCVALUE_MASK;
           for (i = 0; i < E1000_MAX_82574_SYSTIM_REREADS; i++) {
                   /* latch SYSTIMH on read of SYSTIML */
                   systim_next = (cycle_t)er32(SYSTIML);
                   systim_next |= (cycle_t)er32(SYSTIMH) << 32;

                   time_delta = systim_next - systim;
                   temp = time_delta;
 ====>             rem = do_div(temp, incvalue);

This change makes kernel survive this, and users report that
NIC does work after this change.

Since on real hardware incvalue is never zero, this should not affect
real hardware use case.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>