linux/drivers/net/ethernet/rocker
Scott Feldman 4d81db4156 rocker: fix neigh tbl index increment race
rocker->neigh_tbl_next_index is used to generate unique indices for neigh
entries programmed into the device.  The way new indices were generated was
racy with the new prepare-commit transaction model.  A simple fix here
removes the race.  The race was with two processes getting the same index,
one process using prepare-commit, the other not:

Proc A					Proc B

PREPARE phase
get neigh_tbl_next_index

					NONE phase
					get neigh_tbl_next_index
					neigh_tbl_next_index++

COMMIT phase
neigh_tbl_next_index++

Both A and B got the same index.  The fix is to store and increment
neigh_tbl_next_index in the PREPARE (or NONE) phase and use value in COMMIT
phase:

Proc A					Proc B

PREPARE phase
get neigh_tbl_next_index
neigh_tbl_next_index++

					NONE phase
					get neigh_tbl_next_index
					neigh_tbl_next_index++

COMMIT phase
// use value stashed in PREPARE phase

Reported-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-06-15 16:04:21 -07:00
..
Kconfig net: ethernet: rocker: Add dependency to CONFIG_BRIDGE in Kconfig 2014-12-09 15:26:43 -05:00
Makefile
rocker.c rocker: fix neigh tbl index increment race 2015-06-15 16:04:21 -07:00
rocker.h rocker: make checkpatch -f clean 2015-05-12 18:43:56 -04:00