diff options
| author |   Scott Feldman <sfeldma@gmail.com> | 2015-06-12 21:24:40 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2015-06-15 16:04:21 -0700 |
| commit | 4d81db4156caef7b223dde07e50db0144d12a192 (patch) | |
| tree | 26fd99f00ba0c939dd4ecfb1a795e2158882f053 /drivers/net/ethernet/rocker | |
| parent | rocker: gaurd against NULL rocker_port when removing ports (diff) | |
| download | linux-dev-4d81db4156caef7b223dde07e50db0144d12a192.tar.xz linux-dev-4d81db4156caef7b223dde07e50db0144d12a192.zip | |
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>
Diffstat (limited to 'drivers/net/ethernet/rocker')
| -rw-r--r-- | drivers/net/ethernet/rocker/rocker.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/rocker/rocker.c b/drivers/net/ethernet/rocker/rocker.c index c6a6e3c36d90..a9d15590743e 100644 --- a/drivers/net/ethernet/rocker/rocker.c +++ b/drivers/net/ethernet/rocker/rocker.c @@ -2901,10 +2901,10 @@ static void _rocker_neigh_add(struct rocker *rocker, enum switchdev_trans trans, struct rocker_neigh_tbl_entry *entry) { - entry->index = rocker->neigh_tbl_next_index; + if (trans != SWITCHDEV_TRANS_COMMIT) + entry->index = rocker->neigh_tbl_next_index++; if (trans == SWITCHDEV_TRANS_PREPARE) return; - rocker->neigh_tbl_next_index++; entry->ref_count++; hash_add(rocker->neigh_tbl, &entry->entry, be32_to_cpu(entry->ip_addr)); |