linux-kernel - [PATCH 4.14 051/156] nvmet-fc: correct ref counting error when deferred rcv used

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Date:   Fri,  2 Feb 2018 17:57:12 +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, James Smart <james.smart@...adcom.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Christoph Hellwig <hch@....de>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.14 051/156] nvmet-fc: correct ref counting error when deferred rcv used

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

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

From: James Smart <jsmart2021@...il.com>


[ Upstream commit 619c62dcc62b957d17cccde2081cad527b020883 ]

Whenever a cmd is received a reference is taken while looking up the
queue. The reference is removed after the cmd is done as the iod is
returned for reuse. The fod may be reused for a deferred (recevied but
no job context) cmd.  Existing code removes the reference only if the
fod is not reused for another command. Given the fod may be used for
one or more ios, although a reference was taken per io, it won't be
matched on the frees.

Remove the reference on every fod free. This pairs the references to
each io.

Signed-off-by: James Smart <james.smart@...adcom.com>
Reviewed-by: Sagi Grimberg <sagi@...mberg.me>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/nvme/target/fc.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -532,15 +532,15 @@ nvmet_fc_free_fcp_iod(struct nvmet_fc_tg
 
 	tgtport->ops->fcp_req_release(&tgtport->fc_target_port, fcpreq);
 
+	/* release the queue lookup reference on the completed IO */
+	nvmet_fc_tgt_q_put(queue);
+
 	spin_lock_irqsave(&queue->qlock, flags);
 	deferfcp = list_first_entry_or_null(&queue->pending_cmd_list,
 				struct nvmet_fc_defer_fcp_req, req_list);
 	if (!deferfcp) {
 		list_add_tail(&fod->fcp_list, &fod->queue->fod_list);
 		spin_unlock_irqrestore(&queue->qlock, flags);
-
-		/* Release reference taken at queue lookup and fod allocation */
-		nvmet_fc_tgt_q_put(queue);
 		return;
 	}
 
@@ -759,6 +759,9 @@ nvmet_fc_delete_target_queue(struct nvme
 		tgtport->ops->fcp_req_release(&tgtport->fc_target_port,
 				deferfcp->fcp_req);
 
+		/* release the queue lookup reference */
+		nvmet_fc_tgt_q_put(queue);
+
 		kfree(deferfcp);
 
 		spin_lock_irqsave(&queue->qlock, flags);