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    Subject[PATCH 4.14 051/156] nvmet-fc: correct ref counting error when deferred rcv used
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: James Smart <jsmart2021@gmail.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@broadcom.com>
    Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
    Signed-off-by: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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);

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