From 97d82a48d7a7eca6f20b100ae19811134509406e Mon Sep 17 00:00:00 2001 From: Sinan Kaya Date: Mon, 19 Mar 2018 22:47:44 -0400 Subject: [PATCH] IB/mlx4: Eliminate duplicate barriers on weakly-ordered archs Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya Reviewed-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe --- drivers/infiniband/hw/mlx4/qp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c index 04efc05fb531..523028e944ed 100644 --- a/drivers/infiniband/hw/mlx4/qp.c +++ b/drivers/infiniband/hw/mlx4/qp.c @@ -3894,8 +3894,8 @@ out: */ wmb(); - writel(qp->doorbell_qpn, - to_mdev(ibqp->device)->uar_map + MLX4_SEND_DOORBELL); + writel_relaxed(qp->doorbell_qpn, + to_mdev(ibqp->device)->uar_map + MLX4_SEND_DOORBELL); /* * Make sure doorbells don't leak out of SQ spinlock -- 2.25.1