diff options
| author | Jason Gunthorpe <jgg@mellanox.com> | 2019-10-01 12:38:19 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-06 13:08:13 +0100 |
| commit | 45df94c2ad281721db6021ba1466e642828505da (patch) | |
| tree | d434f7451731f2b08bc270c81de201ead8031034 /drivers/infiniband/hw | |
| parent | fb5e59a03021d8ce41ae290d4a5de62bd5bd8ff4 (diff) | |
RDMA/mlx5: Order num_pending_prefetch properly with synchronize_srcu
[ Upstream commit aa116b810ac9077a263ed8679fb4d595f180e0eb ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/infiniband/hw')
| -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 c4ba8838d2c4..96c8a6835592 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -1591,13 +1591,14 @@ 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->page_list) mlx5_ib_invalidate_range(umem_odp, |