From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Chuck Lever <chuck.lever@oracle.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15.y 3/4] svcrdma: Fix retry loop in svc_rdma_send()
Date: Tue,  8 Sep 2026 22:09:30 -0400
Message-ID: <20260909020931.1057969-3-sashal@kernel.org>
In-Reply-To: <20260909020931.1057969-1-sashal@kernel.org>
References: <2026090318-fretted-breach-0806@gregkh>
 <20260909020931.1057969-1-sashal@kernel.org>
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From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit fc709d82dda6405862a681cc425386bfaf049539 ]

Don't call ib_post_send() at all if the transport is already
shutting down.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

[Stable backport preparation for 0fbe20dfe74b]
Keep the 6.1 Send Queue tracepoint signatures: sq_retry takes only the
transport, and sq_post_err takes the transport and error status. This tree
has no local completion ID in svc_rdma_send(). Do not import the upstream
comment about completion releasing the Send context; this branch retains
synchronous completion and caller-managed context lifetime.

Retain the retry-loop fix: check XPT_CLOSE before reserving an SQ entry
or posting, restore the reserved entry and wake waiters only after an
actual post failure, and return -ENOTCONN on either shutdown or failure.
The existing pull-up and reply-error preparation for 0fbe20dfe74b remains
unchanged. No functions are added.

Stable-dep-of: 0fbe20dfe74b ("svcrdma: Reject inline replies that overflow the pull-up buffer")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/sunrpc/xprtrdma/svc_rdma_sendto.c | 28 ++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index d845922bd39c2..fe3369f5c75a6 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -294,8 +294,9 @@ static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
  * @rdma: transport on which to post the WR
  * @ctxt: send ctxt with a Send WR ready to post
  *
- * Returns zero if the Send WR was posted successfully. Otherwise, a
- * negative errno is returned.
+ * Return values:
+ *   %0: @ctxt's Send WR was posted successfully
+ *   %-ENOTCONN: The connection was lost
  */
 int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt)
 {
@@ -311,30 +312,35 @@ int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt)
 				      DMA_TO_DEVICE);
 
 	/* If the SQ is full, wait until an SQ entry is available */
-	while (1) {
+	while (!test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) {
 		if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) {
 			svc_rdma_wake_send_waiters(rdma, 1);
+
+			/* When the transport is torn down, assume
+			 * ib_drain_sq() will trigger enough Send
+			 * completions to wake us. The XPT_CLOSE test
+			 * above should then cause the while loop to
+			 * exit.
+			 */
 			percpu_counter_inc(&svcrdma_stat_sq_starve);
 			trace_svcrdma_sq_full(rdma);
 			wait_event(rdma->sc_send_wait,
 				   atomic_read(&rdma->sc_sq_avail) > 0);
-			if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
-				return -ENOTCONN;
 			trace_svcrdma_sq_retry(rdma);
 			continue;
 		}
 
 		trace_svcrdma_post_send(ctxt);
 		ret = ib_post_send(rdma->sc_qp, wr, NULL);
-		if (ret)
+		if (ret) {
+			trace_svcrdma_sq_post_err(rdma, ret);
+			svc_xprt_deferred_close(&rdma->sc_xprt);
+			svc_rdma_wake_send_waiters(rdma, 1);
 			break;
+		}
 		return 0;
 	}
-
-	trace_svcrdma_sq_post_err(rdma, ret);
-	svc_xprt_deferred_close(&rdma->sc_xprt);
-	svc_rdma_wake_send_waiters(rdma, 1);
-	return ret;
+	return -ENOTCONN;
 }
 
 /**
-- 
2.53.0