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Commit dd6fd213 authored by Chuck Lever's avatar Chuck Lever Committed by J. Bruce Fields
Browse files

svcrdma: Remove DMA map accounting 



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: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent e4eb42ce

include/linux/sunrpc/svc_rdma.h

+0 −2
Original line number Diff line number Diff line
@@ -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 */

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

+0 −1
Original line number Diff line number Diff line
@@ -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)) {

net/sunrpc/xprtrdma/svc_rdma_transport.c

+3 −10
Original line number Diff line number Diff line
@@ -224,25 +224,22 @@ 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)
@@ -944,7 +941,6 @@ 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);
@@ -1256,9 +1252,6 @@ 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) {