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: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 601cb07aa7462bf87cda273f2b6b2a8bf6489eff..43d7c709d11711a818f8f1d8d9315b3e198db6ee 100644 (file)
--- 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 873c2a938d3513b903ac70431375cbbfc33be8c4..283246e0afc2afa0b19f9acd82a529f1d9d35355 100644 (file)
--- 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 da990d7f8b20ce5f724170fc7652ce65084ba4af..a613ebd1dd85c8bbac5de09a394992577080d17a 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -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) {