Return-Path: Received: from mail-io0-f195.google.com ([209.85.223.195]:35929 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933710AbcK2QFB (ORCPT ); Tue, 29 Nov 2016 11:05:01 -0500 Subject: [PATCH v3 05/10] svcrdma: Remove DMA map accounting From: Chuck Lever To: bfields@fieldses.org Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Tue, 29 Nov 2016 11:04:58 -0500 Message-ID: <20161129160458.4477.96653.stgit@klimt.1015granger.net> In-Reply-To: <20161129155521.4477.53561.stgit@klimt.1015granger.net> References: <20161129155521.4477.53561.stgit@klimt.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Clean up: sc_dma_used is not required for correct operation. It is simply a debugging tool to report when svcrdma has leaked DMA maps. However, manipulating an atomic has a measurable CPU cost, and DMA map accounting specific to svcrdma will be meaningless once svcrdma is converted to use the new generic r/w API. A similar kind of debug accounting can be done simply by enabling the IOMMU or by using CONFIG_DMA_API_DEBUG, CONFIG_IOMMU_DEBUG, and CONFIG_IOMMU_LEAK. Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc_rdma.h | 2 -- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 1 - net/sunrpc/xprtrdma/svc_rdma_transport.c | 13 +++---------- 3 files changed, 3 insertions(+), 13 deletions(-) diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h index 601cb07..43d7c70 100644 --- a/include/linux/sunrpc/svc_rdma.h +++ b/include/linux/sunrpc/svc_rdma.h @@ -148,7 +148,6 @@ struct svcxprt_rdma { struct ib_pd *sc_pd; - atomic_t sc_dma_used; spinlock_t sc_ctxt_lock; struct list_head sc_ctxts; int sc_ctxt_used; @@ -200,7 +199,6 @@ static inline void svc_rdma_count_mappings(struct svcxprt_rdma *rdma, struct svc_rdma_op_ctxt *ctxt) { ctxt->mapped_sges++; - atomic_inc(&rdma->sc_dma_used); } /* svc_rdma_backchannel.c */ diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 873c2a9..283246e 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -279,7 +279,6 @@ int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt, frmr->sg); return -ENOMEM; } - atomic_inc(&xprt->sc_dma_used); n = ib_map_mr_sg(frmr->mr, frmr->sg, frmr->sg_nents, NULL, PAGE_SIZE); if (unlikely(n != frmr->sg_nents)) { diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c index 3e68e3d..61ae392 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c @@ -226,25 +226,22 @@ void svc_rdma_unmap_dma(struct svc_rdma_op_ctxt *ctxt) struct svcxprt_rdma *xprt = ctxt->xprt; struct ib_device *device = xprt->sc_cm_id->device; u32 lkey = xprt->sc_pd->local_dma_lkey; - unsigned int i, count; + unsigned int i; - for (count = 0, i = 0; i < ctxt->mapped_sges; i++) { + for (i = 0; i < ctxt->mapped_sges; i++) { /* * Unmap the DMA addr in the SGE if the lkey matches * the local_dma_lkey, otherwise, ignore it since it is * an FRMR lkey and will be unmapped later when the * last WR that uses it completes. */ - if (ctxt->sge[i].lkey == lkey) { - count++; + if (ctxt->sge[i].lkey == lkey) ib_dma_unmap_page(device, ctxt->sge[i].addr, ctxt->sge[i].length, ctxt->direction); - } } ctxt->mapped_sges = 0; - atomic_sub(count, &xprt->sc_dma_used); } void svc_rdma_put_context(struct svc_rdma_op_ctxt *ctxt, int free_pages) @@ -946,7 +943,6 @@ void svc_rdma_put_frmr(struct svcxprt_rdma *rdma, if (frmr) { ib_dma_unmap_sg(rdma->sc_cm_id->device, frmr->sg, frmr->sg_nents, frmr->direction); - atomic_dec(&rdma->sc_dma_used); spin_lock_bh(&rdma->sc_frmr_q_lock); WARN_ON_ONCE(!list_empty(&frmr->frmr_list)); list_add(&frmr->frmr_list, &rdma->sc_frmr_q); @@ -1258,9 +1254,6 @@ static void __svc_rdma_free(struct work_struct *work) if (rdma->sc_ctxt_used != 0) pr_err("svcrdma: ctxt still in use? (%d)\n", rdma->sc_ctxt_used); - if (atomic_read(&rdma->sc_dma_used) != 0) - pr_err("svcrdma: dma still in use? (%d)\n", - atomic_read(&rdma->sc_dma_used)); /* Final put of backchannel client transport */ if (xprt->xpt_bc_xprt) {