linux-kernel - [PATCH 4.8 52/92] xprtrdma: Fix DMAR failure in frwr_op

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Date:   Thu, 17 Nov 2016 11:32:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vasco Steinmetz <linux@...erraum.net>,
        Chuck Lever <chuck.lever@...cle.com>,
        Anna Schumaker <Anna.Schumaker@...app.com>
Subject: [PATCH 4.8 52/92] xprtrdma: Fix DMAR failure in frwr_op_map() after reconnect

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chuck Lever <chuck.lever@...cle.com>

commit 62bdf94a2049822ef8c6d4b0e83cd9c3a1663ab4 upstream.

When a LOCALINV WR is flushed, the frmr is marked STALE, then
frwr_op_unmap_sync DMA-unmaps the frmr's SGL. These STALE frmrs
are then recovered when frwr_op_map hunts for an INVALID frmr to
use.

All other cases that need frmr recovery leave that SGL DMA-mapped.
The FRMR recovery path unconditionally DMA-unmaps the frmr's SGL.

To avoid DMA unmapping the SGL twice for flushed LOCAL_INV WRs,
alter the recovery logic (rather than the hot frwr_op_unmap_sync
path) to distinguish among these cases. This solution also takes
care of the case where multiple LOCAL_INV WRs are issued for the
same rpcrdma_req, some complete successfully, but some are flushed.

Reported-by: Vasco Steinmetz <linux@...erraum.net>
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Tested-by: Vasco Steinmetz <linux@...erraum.net>
Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/sunrpc/xprtrdma/frwr_ops.c  |   37 ++++++++++++++++++++++---------------
 net/sunrpc/xprtrdma/xprt_rdma.h |    3 ++-
 2 files changed, 24 insertions(+), 16 deletions(-)

--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -44,18 +44,20 @@
  * being done.
  *
  * When the underlying transport disconnects, MRs are left in one of
- * three states:
+ * four states:
  *
  * INVALID:	The MR was not in use before the QP entered ERROR state.
- *		(Or, the LOCAL_INV WR has not completed or flushed yet).
- *
- * STALE:	The MR was being registered or unregistered when the QP
- *		entered ERROR state, and the pending WR was flushed.
  *
  * VALID:	The MR was registered before the QP entered ERROR state.
  *
- * When frwr_op_map encounters STALE and VALID MRs, they are recovered
- * with ib_dereg_mr and then are re-initialized. Beause MR recovery
+ * FLUSHED_FR:	The MR was being registered when the QP entered ERROR
+ *		state, and the pending WR was flushed.
+ *
+ * FLUSHED_LI:	The MR was being invalidated when the QP entered ERROR
+ *		state, and the pending WR was flushed.
+ *
+ * When frwr_op_map encounters FLUSHED and VALID MRs, they are recovered
+ * with ib_dereg_mr and then are re-initialized. Because MR recovery
  * allocates fresh resources, it is deferred to a workqueue, and the
  * recovered MRs are placed back on the rb_mws list when recovery is
  * complete. frwr_op_map allocates another MR for the current RPC while
@@ -175,12 +177,15 @@ __frwr_reset_mr(struct rpcrdma_ia *ia, s
 static void
 frwr_op_recover_mr(struct rpcrdma_mw *mw)
 {
+	enum rpcrdma_frmr_state state = mw->frmr.fr_state;
 	struct rpcrdma_xprt *r_xprt = mw->mw_xprt;
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	int rc;
 
 	rc = __frwr_reset_mr(ia, mw);
-	ib_dma_unmap_sg(ia->ri_device, mw->mw_sg, mw->mw_nents, mw->mw_dir);
+	if (state != FRMR_FLUSHED_LI)
+		ib_dma_unmap_sg(ia->ri_device,
+				mw->mw_sg, mw->mw_nents, mw->mw_dir);
 	if (rc)
 		goto out_release;
 
@@ -261,10 +266,8 @@ frwr_op_maxpages(struct rpcrdma_xprt *r_
 }
 
 static void
-__frwr_sendcompletion_flush(struct ib_wc *wc, struct rpcrdma_frmr *frmr,
-			    const char *wr)
+__frwr_sendcompletion_flush(struct ib_wc *wc, const char *wr)
 {
-	frmr->fr_state = FRMR_IS_STALE;
 	if (wc->status != IB_WC_WR_FLUSH_ERR)
 		pr_err("rpcrdma: %s: %s (%u/0x%x)\n",
 		       wr, ib_wc_status_msg(wc->status),
@@ -287,7 +290,8 @@ frwr_wc_fastreg(struct ib_cq *cq, struct
 	if (wc->status != IB_WC_SUCCESS) {
 		cqe = wc->wr_cqe;
 		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-		__frwr_sendcompletion_flush(wc, frmr, "fastreg");
+		frmr->fr_state = FRMR_FLUSHED_FR;
+		__frwr_sendcompletion_flush(wc, "fastreg");
 	}
 }
 
@@ -307,7 +311,8 @@ frwr_wc_localinv(struct ib_cq *cq, struc
 	if (wc->status != IB_WC_SUCCESS) {
 		cqe = wc->wr_cqe;
 		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+		frmr->fr_state = FRMR_FLUSHED_LI;
+		__frwr_sendcompletion_flush(wc, "localinv");
 	}
 }
 
@@ -327,8 +332,10 @@ frwr_wc_localinv_wake(struct ib_cq *cq,
 	/* WARNING: Only wr_cqe and status are reliable at this point */
 	cqe = wc->wr_cqe;
 	frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-	if (wc->status != IB_WC_SUCCESS)
-		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+	if (wc->status != IB_WC_SUCCESS) {
+		frmr->fr_state = FRMR_FLUSHED_LI;
+		__frwr_sendcompletion_flush(wc, "localinv");
+	}
 	complete(&frmr->fr_linv_done);
 }
 
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -207,7 +207,8 @@ struct rpcrdma_rep {
 enum rpcrdma_frmr_state {
 	FRMR_IS_INVALID,	/* ready to be used */
 	FRMR_IS_VALID,		/* in use */
-	FRMR_IS_STALE,		/* failed completion */
+	FRMR_FLUSHED_FR,	/* flushed FASTREG WR */
+	FRMR_FLUSHED_LI,	/* flushed LOCALINV WR */
 };
 
 struct rpcrdma_frmr {