| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 19/50] ixgbe: Prevent u8 wrapping of ITR value to something less than 10us | Date | Wed, 18 Sep 2019 08:19:02 +0200 |
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From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
commit 377228accbbb8b9738f615d791aa803f41c067e0 upstream.
There were a couple cases where the ITR value generated via the adaptive ITR scheme could exceed 126. This resulted in the value becoming either 0 or something less than 10. Switching back and forth between a value less than 10 and a value greater than 10 can cause issues as certain hardware features such as RSC to not function well when the ITR value has dropped that low.
CC: stable@vger.kernel.org Fixes: b4ded8327fea ("ixgbe: Update adaptive ITR algorithm") Reported-by: Gregg Leventhal <gleventhal@janestreet.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Tested-by: Andrew Bowers <andrewx.bowers@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -2626,7 +2626,7 @@ adjust_by_size: /* 16K ints/sec to 9.2K ints/sec */ avg_wire_size *= 15; avg_wire_size += 11452; - } else if (avg_wire_size <= 1980) { + } else if (avg_wire_size < 1968) { /* 9.2K ints/sec to 8K ints/sec */ avg_wire_size *= 5; avg_wire_size += 22420; @@ -2659,6 +2659,8 @@ adjust_by_size: case IXGBE_LINK_SPEED_2_5GB_FULL: case IXGBE_LINK_SPEED_1GB_FULL: case IXGBE_LINK_SPEED_10_FULL: + if (avg_wire_size > 8064) + avg_wire_size = 8064; itr += DIV_ROUND_UP(avg_wire_size, IXGBE_ITR_ADAPTIVE_MIN_INC * 64) * IXGBE_ITR_ADAPTIVE_MIN_INC;
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