[ 13/72] bnx2x: fix occasional statistics off-by-4GB error

Greg Kroah-Hartman
2013-03-26T23:25:24Z

From: Maciej Żenczykowski <maze@google.com>

[ Upstream commit b009aac12cd0fe34293c68af8ac48b85be3bd858 ]

The UPDATE_QSTAT function introduced on February 15, 2012
in commit 1355b704b9ba "bnx2x: consistent statistics after
internal driver reload" incorrectly fails to handle overflow
during addition of the lower 32-bit field of a stat.

This bug is present since 3.4-rc1 and should thus be considered
a candidate for stable 3.4+ releases.

Google-Bug-Id: 8374428
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Cc: Mintz Yuval <yuvalmin@broadcom.com>
Acked-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h
@@ -439,8 +439,9 @@ struct bnx2x_fw_port_stats_old {

#define UPDATE_QSTAT(s, t) \
do { \
- qstats->t##_hi = qstats_old->t##_hi + le32_to_cpu(s.hi); \
qstats->t##_lo = qstats_old->t##_lo + le32_to_cpu(s.lo); \
+ qstats->t##_hi = qstats_old->t##_hi + le32_to_cpu(s.hi) \
+ + ((qstats->t##_lo < qstats_old->t##_lo) ? 1 : 0); \
} while (0)

#define UPDATE_QSTAT_OLD(f) \