diff options
| author | Denys Vlasenko <dvlasenk@redhat.com> | 2016-04-20 15:45:55 (GMT) |
|---|---|---|
| committer | Jeff Kirsher <jeffrey.t.kirsher@intel.com> | 2016-05-13 21:52:31 (GMT) |
| commit | a07fd74d5ea9c45a5c6e41f7cb4b997cf40d50f3 (patch) | |
| tree | 51644535024b284fdfbcf890fcf7029f2db42bc2 | |
| parent | fb5277f2c2e4db4a29740ff071072a688892d2df (diff) | |
| download | linux-a07fd74d5ea9c45a5c6e41f7cb4b997cf40d50f3.tar.xz | |
e1000e: e1000e_cyclecounter_read(): fix er32(SYSTIML) overflow check
If two consecutive reads of the counter are the same, it is also
not an overflow. "systimel_1 < systimel_2" should be
"systimel_1 <= systimel_2".
Before the patch, we could perform an *erroneous* correction:
Let's say that systimel_1 == systimel_2 == 0xffffffff.
"systimel_1 < systimel_2" is false, we think it's an overflow,
we read "systimeh = er32(SYSTIMH)" which meanwhile had incremented,
and use "(systimeh << 32) + systimel_2" value which is 2^32 too large.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: intel-wired-lan@lists.osuosl.org
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
| -rw-r--r-- | drivers/net/ethernet/intel/e1000e/netdev.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c index 4969f64..02c64bc 100644 --- a/drivers/net/ethernet/intel/e1000e/netdev.c +++ b/drivers/net/ethernet/intel/e1000e/netdev.c @@ -4287,7 +4287,7 @@ static cycle_t e1000e_cyclecounter_read(const struct cyclecounter *cc) systimeh = er32(SYSTIMH); systimel_2 = er32(SYSTIML); /* Check for overflow. If there was no overflow, use the values */ - if (systimel_1 < systimel_2) { + if (systimel_1 <= systimel_2) { systim = (cycle_t)systimel_1; systim |= (cycle_t)systimeh << 32; } else { |