From 296e3a2aad09d328f22e54655c3d736033fe1ae8 Mon Sep 17 00:00:00 2001 From: Moni Shoua Date: Tue, 23 Jul 2019 09:57:30 +0300 Subject: IB/mlx5: Prevent concurrent MR updates during invalidation The device requires that memory registration work requests that update the address translation table of a MR will be fenced if posted together. This scenario can happen when address ranges are invalidated by the mmu in separate concurrent calls to the invalidation callback. We prefer to block concurrent address updates for a single MR over fencing since making the decision if a WQE needs fencing will be more expensive and fencing all WQEs is a too radical choice. Further, it isn't clear that this code can even run safely concurrently, so a lock is a safer choice. Fixes: b4cfe447d47b ("IB/mlx5: Implement on demand paging by adding support for MMU notifiers") Link: https://lore.kernel.org/r/20190723065733.4899-8-leon@kernel.org Signed-off-by: Moni Shoua Reviewed-by: Artemy Kovalyov Signed-off-by: Leon Romanovsky Reviewed-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe --- drivers/infiniband/hw/mlx5/odp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c index 36ba901cc9a5..81da82050d05 100644 --- a/drivers/infiniband/hw/mlx5/odp.c +++ b/drivers/infiniband/hw/mlx5/odp.c @@ -246,7 +246,7 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start, * overwrite the same MTTs. Concurent invalidations might race us, * but they will write 0s as well, so no difference in the end result. */ - + mutex_lock(&umem_odp->umem_mutex); for (addr = start; addr < end; addr += BIT(umem_odp->page_shift)) { idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift; /* @@ -278,6 +278,7 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start, idx - blk_start_idx + 1, 0, MLX5_IB_UPD_XLT_ZAP | MLX5_IB_UPD_XLT_ATOMIC); + mutex_unlock(&umem_odp->umem_mutex); /* * We are now sure that the device will not access the * memory. We can safely unmap it, and mark it as dirty if -- cgit v1.2.3-55-g7522