diff options
| author | Jason Gunthorpe <jgg@mellanox.com> | 2019-10-01 18:38:19 +0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@mellanox.com> | 2019-10-04 21:54:22 +0300 |
| commit | aa116b810ac9077a263ed8679fb4d595f180e0eb (patch) | |
| tree | 0e00e8d84c48e8ce53d2035207be218238e1ebf1 /drivers/infiniband | |
| parent | 9dc775e7f5508f848661bbfb2e15683affb85f24 (diff) | |
| download | linux-aa116b810ac9077a263ed8679fb4d595f180e0eb.tar.xz | |
RDMA/mlx5: Order num_pending_prefetch properly with synchronize_srcu
During destroy setting live = 0 and then synchronize_srcu() prevents
num_pending_prefetch from incrementing, and also, ensures that all work
holding that count is queued on the WQ. Testing before causes races of the
form:
CPU0 CPU1
dereg_mr()
mlx5_ib_advise_mr_prefetch()
srcu_read_lock()
num_pending_prefetch_inc()
if (!live)
live = 0
atomic_read() == 0
// skip flush_workqueue()
atomic_inc()
queue_work();
srcu_read_unlock()
WARN_ON(atomic_read()) // Fails
Swap the order so that the synchronize_srcu() prevents this.
Fixes: a6bc3875f176 ("IB/mlx5: Protect against prefetch of invalid MR")
Link: https://lore.kernel.org/r/20191001153821.23621-5-jgg@ziepe.ca
Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'drivers/infiniband')
| -rw-r--r-- | drivers/infiniband/hw/mlx5/mr.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index e7f840f306e4..0ee8fa01177f 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -1609,13 +1609,14 @@ static void dereg_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr) */ mr->live = 0; + /* Wait for all running page-fault handlers to finish. */ + synchronize_srcu(&dev->mr_srcu); + /* dequeue pending prefetch requests for the mr */ if (atomic_read(&mr->num_pending_prefetch)) flush_workqueue(system_unbound_wq); WARN_ON(atomic_read(&mr->num_pending_prefetch)); - /* Wait for all running page-fault handlers to finish. */ - synchronize_srcu(&dev->mr_srcu); /* Destroy all page mappings */ if (!umem_odp->is_implicit_odp) mlx5_ib_invalidate_range(umem_odp, |