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svcrdma: Remove DMA map accounting

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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>
This commit is contained in:
Chuck Lever 2016-11-29 11:04:58 -05:00 committed by J. Bruce Fields
parent e4eb42cecc
commit dd6fd213b0
3 changed files with 3 additions and 13 deletions
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2
include/linux/sunrpc/svc_rdma.h
View File

@ -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 */

1
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View File

@ -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)) {

13
net/sunrpc/xprtrdma/svc_rdma_transport.c
View File

@ -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) {