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ixgbe: Prevent u8 wrapping of ITR value to something less than 10us

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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: b4ded8327f ("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>
This commit is contained in:
Alexander Duyck 2019-09-04 08:07:11 -07:00 • committed by Greg Kroah-Hartman
parent 7cbd49cf0d
commit 5b5f14601e
1 changed files with 3 additions and 1 deletions
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4
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
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@ -2626,7 +2626,7 @@ static void ixgbe_update_itr(struct ixgbe_q_vector *q_vector,
/* 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 @@ static void ixgbe_update_itr(struct ixgbe_q_vector *q_vector,
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;