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Subject: [PATCH v1 5/8] xprtrdma: Improve commentary around
 rpcrdma_reps_unmap()
From:   Chuck Lever <chuck.lever@oracle.com>
To:     linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org
Date:   Wed, 31 Mar 2021 15:36:29 -0400
Message-ID: <161721938951.515226.17560651611000798100.stgit@manet.1015granger.net>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index fe250d554695..b68fc81a78fb 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1034,6 +1034,10 @@ static void rpcrdma_rep_put(struct rpcrdma_buffer *buf,
 	llist_add(&rep->rr_node, &buf->rb_free_reps);
 }
 
+/* Caller must ensure the QP is quiescent (RQ is drained) before
+ * invoking this function, to guarantee rb_all_reps is not
+ * changing.
+ */
 static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt)
 {
 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
@@ -1041,7 +1045,7 @@ static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt)
 
 	list_for_each_entry(rep, &buf->rb_all_reps, rr_all) {
 		rpcrdma_regbuf_dma_unmap(rep->rr_rdmabuf);
-		rep->rr_temp = true;
+		rep->rr_temp = true;	/* Mark this rep for destruction */
 	}
 }