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authorDenys Vlasenko <dvlasenk@redhat.com>2016-04-20 15:45:55 (GMT)
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>2016-05-13 21:52:31 (GMT)
commita07fd74d5ea9c45a5c6e41f7cb4b997cf40d50f3 (patch)
tree51644535024b284fdfbcf890fcf7029f2db42bc2
parentfb5277f2c2e4db4a29740ff071072a688892d2df (diff)
downloadlinux-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.c2
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 {