[PATCH v4 3/6] RDMA/i40iw: Eliminate duplicate barriers on weakly-ordered archs
From: jgg@ziepe.ca (Jason Gunthorpe)
Date: 2018-03-21 20:02:57
Also in:
linux-arm-msm, linux-rdma, lkml
On Mon, Mar 19, 2018 at 10:47:45PM -0400, Sinan Kaya wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/infiniband/hw/i40iw/i40iw_uk.c b/drivers/infiniband/hw/i40iw/i40iw_uk.c index 8afa5a6..7f0ebed 100644 +++ b/drivers/infiniband/hw/i40iw/i40iw_uk.c@@ -723,7 +723,7 @@ static void i40iw_cq_request_notification(struct i40iw_cq_uk *cq, wmb(); /* make sure WQE is populated before valid bit is set */ - writel(cq->cq_id, cq->cqe_alloc_reg); + writel_relaxed(cq->cq_id, cq->cqe_alloc_reg); }
Ah, this one is probably not OK, i40iw_cq_request_notification is called here: spin_lock_irqsave(&iwcq->lock, flags); ukcq->ops.iw_cq_request_notification(ukcq, cq_notify); spin_unlock_irqrestore(&iwcq->lock, flags); So this needs to add mmmiomb(); to keep the same semantics. Generally I think you need to be very careful to ensure that any conversion to _relaxed isn't contained by a spinlock, or the mmiomb() is present. Maybe even do a first series with this obviously correct pattern: wmb(); writel() -> writel_relaxed() writel() -> writel_relaxed() [..] mmiowmb(); Jason