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Commit 81fa3275 authored by Chuck Lever's avatar Chuck Lever Committed by J. Bruce Fields
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svcrdma: Poll CQs in "workqueue" mode 



svcrdma calls svc_xprt_put() in its completion handlers, which
currently run in IRQ context.

However, svc_xprt_put() is meant to be invoked in process context,
not in IRQ context. After the last transport reference is gone, it
directly calls a transport release function that expects to run in
process context.

Change the CQ polling modes to IB_POLL_WORKQUEUE so that svcrdma
invokes svc_xprt_put() only in process context. As an added benefit,
bottom half-disabled spin locking can be eliminated from I/O paths.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent a3ab867f

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

+3 −3
Original line number Diff line number Diff line
@@ -606,12 +606,12 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) 


	dprintk("svcrdma: rqstp=%p\n", rqstp);



	spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);

	spin_lock(&rdma_xprt->sc_rq_dto_lock);

	if (!list_empty(&rdma_xprt->sc_read_complete_q)) {

		ctxt = list_first_entry(&rdma_xprt->sc_read_complete_q,

					struct svc_rdma_op_ctxt, list);

		list_del(&ctxt->list);

		spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);

		spin_unlock(&rdma_xprt->sc_rq_dto_lock);

		rdma_read_complete(rqstp, ctxt);

		goto complete;

	} else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
@@ -623,7 +623,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) 
		clear_bit(XPT_DATA, &xprt->xpt_flags);

		ctxt = NULL;

	}

	spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);

	spin_unlock(&rdma_xprt->sc_rq_dto_lock);

	if (!ctxt) {

		/* This is the EAGAIN path. The svc_recv routine will

		 * return -EAGAIN, the nfsd thread will go to call into

net/sunrpc/xprtrdma/svc_rdma_transport.c

+13 −13
Original line number Diff line number Diff line
@@ -188,7 +188,7 @@ struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt) 
{

	struct svc_rdma_op_ctxt *ctxt = NULL;



	spin_lock_bh(&xprt->sc_ctxt_lock);

	spin_lock(&xprt->sc_ctxt_lock);

	xprt->sc_ctxt_used++;

	if (list_empty(&xprt->sc_ctxts))

		goto out_empty;
@@ -196,7 +196,7 @@ struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt) 
	ctxt = list_first_entry(&xprt->sc_ctxts,

				struct svc_rdma_op_ctxt, list);

	list_del(&ctxt->list);

	spin_unlock_bh(&xprt->sc_ctxt_lock);

	spin_unlock(&xprt->sc_ctxt_lock);



out:

	ctxt->count = 0;
@@ -208,15 +208,15 @@ struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt) 
	/* Either pre-allocation missed the mark, or send

	 * queue accounting is broken.

	 */

	spin_unlock_bh(&xprt->sc_ctxt_lock);

	spin_unlock(&xprt->sc_ctxt_lock);



	ctxt = alloc_ctxt(xprt, GFP_NOIO);

	if (ctxt)

		goto out;



	spin_lock_bh(&xprt->sc_ctxt_lock);

	spin_lock(&xprt->sc_ctxt_lock);

	xprt->sc_ctxt_used--;

	spin_unlock_bh(&xprt->sc_ctxt_lock);

	spin_unlock(&xprt->sc_ctxt_lock);

	WARN_ONCE(1, "svcrdma: empty RDMA ctxt list?\n");

	return NULL;

}
@@ -253,10 +253,10 @@ void svc_rdma_put_context(struct svc_rdma_op_ctxt *ctxt, int free_pages) 
		for (i = 0; i < ctxt->count; i++)

			put_page(ctxt->pages[i]);



	spin_lock_bh(&xprt->sc_ctxt_lock);

	spin_lock(&xprt->sc_ctxt_lock);

	xprt->sc_ctxt_used--;

	list_add(&ctxt->list, &xprt->sc_ctxts);

	spin_unlock_bh(&xprt->sc_ctxt_lock);

	spin_unlock(&xprt->sc_ctxt_lock);

}



static void svc_rdma_destroy_ctxts(struct svcxprt_rdma *xprt)
@@ -921,14 +921,14 @@ struct svc_rdma_fastreg_mr *svc_rdma_get_frmr(struct svcxprt_rdma *rdma) 
{

	struct svc_rdma_fastreg_mr *frmr = NULL;



	spin_lock_bh(&rdma->sc_frmr_q_lock);

	spin_lock(&rdma->sc_frmr_q_lock);

	if (!list_empty(&rdma->sc_frmr_q)) {

		frmr = list_entry(rdma->sc_frmr_q.next,

				  struct svc_rdma_fastreg_mr, frmr_list);

		list_del_init(&frmr->frmr_list);

		frmr->sg_nents = 0;

	}

	spin_unlock_bh(&rdma->sc_frmr_q_lock);

	spin_unlock(&rdma->sc_frmr_q_lock);

	if (frmr)

		return frmr;
@@ -941,10 +941,10 @@ 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);

		spin_lock_bh(&rdma->sc_frmr_q_lock);

		spin_lock(&rdma->sc_frmr_q_lock);

		WARN_ON_ONCE(!list_empty(&frmr->frmr_list));

		list_add(&frmr->frmr_list, &rdma->sc_frmr_q);

		spin_unlock_bh(&rdma->sc_frmr_q_lock);

		spin_unlock(&rdma->sc_frmr_q_lock);

	}

}
@@ -1026,13 +1026,13 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt) 
		goto errout;

	}

	newxprt->sc_sq_cq = ib_alloc_cq(dev, newxprt, newxprt->sc_sq_depth,

					0, IB_POLL_SOFTIRQ);

					0, IB_POLL_WORKQUEUE);

	if (IS_ERR(newxprt->sc_sq_cq)) {

		dprintk("svcrdma: error creating SQ CQ for connect request\n");

		goto errout;

	}

	newxprt->sc_rq_cq = ib_alloc_cq(dev, newxprt, newxprt->sc_rq_depth,

					0, IB_POLL_SOFTIRQ);

					0, IB_POLL_WORKQUEUE);

	if (IS_ERR(newxprt->sc_rq_cq)) {

		dprintk("svcrdma: error creating RQ CQ for connect request\n");

		goto errout;